Hello! My name is Jessica, I am a physician assistant, and one of the providers at Aesthetic Skin in Winnetka and Chicago. This is a great question. The line you're experiencing that resembles a double chin when you smile is likely due to the dynamic movement of your facial muscles and the natural folding of the skin in that area during expression. While you might like your appearance at rest, this dynamic line can be addressed with a few different approaches, depending on its exact cause and your preferences. One option is a small amount of Botox injected strategically in the muscles of your lower face and upper neck that contribute to this folding when you smile. By carefully relaxing these muscles, the line may become less prominent during animation without significantly affecting your resting appearance. This approach is temporary, typically lasting 3-4 months. Another option to consider is dermal fillers. If the line is partly due to a slight loss of volume or a natural crease in that area, a small amount of filler can be placed to subtly smooth it out. This can provide a longer-lasting improvement compared to Botox, typically lasting anywhere from 6 months to over a year, depending on the type of filler used. I hope this helps and best of luck!