Too Young for Ulthera?

No, 20's is not too young. In your 20's you are still producing your own collagen, so it would work great for prevention!

I prefer to do Ultherapy after there is evidence that the treatment can help improve a situation that already exists, rather than treating before the condition occurs. It's not an inexpensive treatment,  there is some degree of discomfort, and although very safe, there are risks and I would rather not subject this procedure on a young person who wants to try to prevent the aging process. If at 29 years of age, there is some sagging that has occurred already; if there is some formation of smile folds from cheeks that have started to fall, or upper eyelids that are "hooding" from a lowering forehead, then, that patient might be considered a candidate for Ultherapy, and this would be determined during an examination. 

Ultherapy builds collagen and is optimal for young patients who have the ability to stimulate collagen production. As a preventative measure, it is an excellent modality for the jowls and neck. Raffy Karamanoukian, Los Angeles

Ultherapy is a noninvasive skin lifting technology that works by stimulating a healing response for new collagen. At 29 it seems unlikely that there is enough skin laxity to see much of a difference. On the other hand, if the laxity is significant then a surgical facelift is best, so that is why the best age group is from late 30's to early 50's.

Ultherapy is used when there is skin laxity and there is no age at which it cannot be effective. If you have skin laxity,, you may be an apporopriate candidate. Collagen stimulation with treatment will surely help prevent advanced skin laxity, even at the tender age of 29. 

Your age is definitely not a negative, in fact it helps Ultherapy be even more effective. Your body is producing more collagen at a younger age which helps Ultherapy's effectiveness.

I don't think age should be a determinant in deciding whether it's a good solution. Ulthera can restore skin that has lost its elasticity even though you're still in your 20s. Your age can even improve your results, as it is generally thought that collagen is remodeled better at younger ages, which ultimately leads to better results.