How to improve my lower third? (Photo)

Your frontal contours indicate that you 'need' jawline augmentation to establish a well defined appearance and facial contour. The procedure is done intraorally and can extend from the chin to the angles of the jaw so that a blended and balanced result occurs. very cosmetic and straightforward

 Hi, I have performed many facial shaping procedures using dermal fillers, silastic facial implants (cheek and lip implants, chin), liposuction and/or facelifts for over 30 years.  Following my beauty principles, men look chiseled and handsome with angularity in the cheeks, chin and mandibular angles.  From the photos, your cheeks are already angular as you mentioned.  From the front view, I suspect that the chin is weak ( side view would help to confirm ) based upon the lack of a mental groove below the lower lip.  The following procedures would create angularity and balance in the lower third of the face and a more ruggedly handsome face.Chin augmentation, using a chin implant, to add projection to the chin creating harmony and balance to the lower face.  I have performed many facial shaping procedures, including Chin Augmentation with dermal fillers or silastic chin implants, for over 30 years.  When the chin is weak, this creates an imbalance making the nose appear larger, the mid face top heavy, the lower face looks short, de-emphasizes the lips and allows early formation of a "double chin".  Proper placement of a silastic chin implant adds forward projection to the chin thereby creating harmony and balance to the lower face.  Using the same incision, liposuction can be performed to reduce the fat and further shape the neck.  Excess skin, from below the chin, can also be removed through the same incision.  I have found that placement of a silastic chin implant, through a small curved incision under the chin (also allows excess skin removal) to be very safe, quick, highly effective and far less invasive than a sliding genioplasty (requires extensive tissue dissection, bone cuts and placement of metal screws and plates to secure the cut bone segments).  I perform chin implant surgery in 30 minutes or less, often using a local anesthetic alone.  In my opinion, you are a good candidate for chin implant surgery.  I do use dermal filler to augment the chin but a silastic chin implant proves to be far more "cost effective" over the years.  
Augmentation of the mandibular angles using a dermal filler (jaw implants have too many unwanted side effects IMHO) to add volume, angularity and flare to the jaw line.
Hope this helps.