Lower facelift at age 36 years

With the amount of sagging (very slight) you describe I would very much hesitate to recommend a surgical procedure.  You need to talk with your surgeon (or get a second opinion) about alternatives.  The downturn of the mouth may very well be able to be improved with some form of filler to "lift" the corners.  Radiesse, Juvederm etc., are all quite good for this but be sure you go to a physician experienced in filler techniques and stay away from non-physician injectors.  Also, the mild sagging you describe may be amenable to tightening with various laser techniques (Fraxel re:Pair if you also need to resurface the skin for age or sunspots, enlarged pores, fine wrinkles, etc;  Thermage which is just for tightening but can be painful, and laser assisted liposculpture to remove fat under the chin and neck but also tighten and define the neck and jawline; etc)  Again, you need to consult with a surgeon experienced in the techniques described above and who will give you an honest opinion after ascertaining your goals and expectations as to whether any of these procedures can meet those goals.