The lower half of my face is saggy and has no definition. How can this be fixed? (Photos)

A consult in person with a plastic surgeon will be best to determine your best option. It is difficult to fully tell because the turtleneck is covering your neck, but it appears that a mini-lift (lateral extended sub-SMAS rhytidectomy) would be a great choice. If on exam you also have platysmal bands, then a platysmaplasty may also be added. Lifting the SMAS with full undermining should lift your jowls and help define your neckline, jawline and soften your marionettes. This can often be done without general anesthesia, but that is an important discussion to have with your surgeon.   

FaceTite can internally tighten the skin in the lower face and neck. After all the skin has been heated and contracted, we shape the neck with liposuction to give definition and remove stubborn pockets of fat. In one quick treatment, we can tighten skin, remove fat, and contour the lower face, jawline, and jowls with only a weekend of downtime. Keep in mind that combination approaches will give you a more significant improvement as opposed to a single procedure. I recommend getting a consultation with a board-certified cosmetic dermatologist and facial sculpting expert. Best, Dr. Emer

Hi Dannipf,
Thank you for sharing your question and images with us,
Thank you for including a photographs with your question.  It makes a meaningful discussion about relevant therapies a little more attainable. 
One of the most important aspects of whether or not you are a candidate for a facelift is your goals for the procedure.  A lower facelift is a great treatment for sagging jowls and to improve the contours of the neck.  The primary way this is accomplished is by removing excess skin and secondarily by elevating some of the deeper tissues. 
If your concern is jowl descent, loss of neckline or submental skin and fat accumulation, a lower facelift is without a doubt the best treatment for this area. 
There are a number of surgical and non-surgical options that can improve one's cosmetic appearance: fillers, skin-tightening procedures, lasers, fat contouring, and facelifts. Each has benefits and drawbacks. Mini procedures do not produce the long-lasting maximum 
Once you have done your research, and chosen your Surgeon, a Consultation will give you the opportunity to discuss your requirements, ask any questions and have an examination.  

Hope this has been of help

All the best and good luck

In person exam is essential. From the limited photos it appears that you may benefit from facelift/neck lift. I suggest that you seek an experienced Board Certified PS for in person evaluation

A mini facelift is a great option for many people. The recovery & downtime is very minimal. There are usually no drains, most people can go out the same day, you can shower the next day, there're no scars behind the ears and you can wear your hair up anytime and most patients take no pain medicine. There are never any guarantees of course with any procedure whether it is surgical or nonsurgical in nature. I'd recommend not getting into the mindset of thinking the jowls or neck skin will be 100% gone with a mini facelift or neck lift as this might lead to disappointment. It is always best to consider that an area will be improved and discuss how much with your plastic surgeon. 
Surgery is not for everyone. In today's day and age, there are many nonsurgical options to consider although surgery usually gets the most improvement specifically of the neck and jowls.
I would recommend that you see a board-certified plastic surgeon in your area that is a member of both ASPS & ASAPS and performs a lot of mini facelifts and neck lifts but also offers all the nonsurgical options such as injectables and laser treatments. Go over your concerns with them and make sure above all, you walk out of there with several options and an idea of the pros and cons to each of them as well as realistic expectations. 
I hope this helps. If it does, please take a moment to up vote this answer on the “respond” button on the top right.  Have a great day.

Thank you for your question.  Yes I believe after review your pictures that a lower facelift can firm your face and give you a better definition of your face and neck.   If your desire is to treat  the lower part of your face and give you a better jaw line and more define neck is what a  lower face lift with the deep plane is design to do.

 Hi, looking at the photos there is a lack of mid face bony volume (cheeks) and jowls are present in the lower face.  Despite being only 36 years of age, these factors combine to create an elongated, rectangularly-shaped face.  I have performed many SMAS facelifts for over 30 years and have performed many minimally, invasive SMAS facelifts.  
 Following my beauty principles, women look the most feminine, youthful and attractive with heart shaped faces.  Heart shaped faces have cheeks that are full and round in the front.  This would require restoration of the front volume of the cheeks with a dermal filler or by using silastic cheek implants (for a permanent enhancement) to create full, round cheeks that will feminize the entire face.  As described below, fat injection or transfer should be avoided due the lack of reliable results.
 If you have "jowls” these are sagging facial tissues and the main indication for some form of a SMAS facelift.  The underlying SMAS layer, of the face, must be dissected, lifted, trimmed and re-sutured (not merely folded or suspended with threads or sutures that will not last).  The excess skin is then removed and the facelift incisions closed.
 My most popular SMAS facelift is the minimally invasive, short incision SMAS facelift that has all the benefits of more invasive facelifts (traditional, mid-face, deep plane, cheek lift and subperiosteal facelifts) but with these added benefits:
very small incisions and no incisions extend or are placed within the hair.
minimal tissue dissection = less bruising and swelling = rapid recovery ( several days instead of weeks or months with the more invasive type facelifts mentioned)
can be performed in 90 minutes or less, with or without general anesthesia
proper SMAS Imbrication technique
no incisions within the hair = no hair loss
excess fat can be removed from the face and neck
excess skin removed from the face and neck
cheeks, chin and jaw line can be augmented with dermal fillers (I prefer Restylane Lyft) or facial implants
most patients fly back home to parts all over the world in as little as 3 days post-op
 I combine facial shaping with every facelift procedure.  When jowls are present, these should be done in concert and not alone or separately in order to create a naturally, more attractive face. The reality is, there are many different ways to perform a facelift from incision length, incision placement, level of tissue dissection (skin only, SMAS, Deep Plane, Subperiosteal), different degrees of tissue undermining, how to lift and support (imbrication versus plication of the SMAS layer), how much excess skin to trim, is excess fat going to be reduced and finally will the overall shape of the face be made more feminine or masculine (while avoiding the over pulled, windswept appearance).  Price is determined by the reputation, location and experience of the Facelift Surgeon.
 In my humble opinion however, there are some basic requirements that must be met in order for a facelift to be "effective", yielding "aesthetic pleasing" and "naturally attractive" results.  These include: 
 1. Some type of incision either curved around the front (preferred) or straight in front of the ear.  This is how excess skin is removed which is not possible with an incision behind the ear alone.  If you have so little excess skin on the face that "none" needs to be removed you are not a candidate for a facelift in the first place.
2. The facelift must address correction and softening of the "jowls" using a long lasting and effective technique.  If you have "jowls” these are sagging facial tissues and the main indication for some form of a SMAS facelift.  The underlying SMAS layer, of the face, must be dissected, lifted, trimmed and re-sutured (not merely folded or suspended with threads or sutures that will not last).  The excess skin is then removed and the facelift incisions closed.
3. Facial shaping must be combined to properly shape the cheeks, chin, jaw line and lips for feminizing or masculinizing the face as the case may be.  I have performed many facial shaping procedures using dermal fillers, facial implants (cheek, chin), liposuction and/or facelifts for over 30 years.  In my experience and despite its recent increase in popularity, fat transfer (fat injection) offers "far" less of a reliable and predictable volume for facial shaping than an off the shelf dermal filler or silastic facial implant.  For that reason, I do not use fat to shape the cheeks, chin, lips or jaw line.  Tissue physiology is quite simple.  Tissue requires a blood supply in and out as well as lymphatic connections to remain viable and alive.  Once fat is removed from the body all of these things have been disrupted.  Just because the removed fat is mixed with PRP or something else doesn't make the blood and lymphatics magically re-appear.  The fat at that point is not living tissue which means that it's prone to being dissolved by the body (most likely in an uneven and unpredictable manner).  Injecting fat back into the face does not create the required elements to make the fat living tissue once again.  So the argument that fat is alive and viable in the face once it's been removed and re-injected makes no sense to me as a physician and surgeon.
 The other issue that I have with fat transfer is the lack of precision.  Fat is thick by nature which means it's not the same consistency as an off the shelf dermal filler.  Fat injections use an increased volume injected in an attempt to compensate for the volume loss that "will" happen.  This means a lack of specific shape and volume that simply can not begin to compare with the specificity of using a silastic facial implant of a "known" shape and volume.  In that regard fat offers too much of an unknown to make it a reliable and predictable method for facial shaping.  There's a significant difference between a 3mm and 5mm thick cheek implant.  You can imagine the magnitude of difference there is between retaining 60% of 25cc's of fat versus 35%.  In my humble opinion, I just don’t see how fat could possibly be used to precisely shape facial features?
Hope this helps.