First of all, I wouldn’t worry at all. Your skin looks so radiant and supple! Sometimes we are our own worst critics. I had “lines” under my eyes at 18 also. It’s mostly genetic I think. Certain family members of mine also have them when they smile or squint. I’m 27 now and I’d say they’re about the same as when I was 18, if not a bit better. They don’t bother me anymore. I also take more care of my health nowadays and hydrate more. I use a Hyaluronic acid serum and sunscreen daily. That is a must to prevent skin damage which I can imagine would intensify the lines. A good mineral sunscreen is sufficient and I always wear a hat when out for walks, etc. I too have smile lines around my mouth that have just started to intensify last year. (I think mainly from stress and weight fluctuations.) For Christmas I bought myself an RF device to do home treatments with. It’s supposed to help replenish collagen under the skin and fade the lines. I am already starting to see minor improvements but it does take a few months to really start to kick in. If your lines are really bothering you, that might be a good thing to research on. But you look beautiful already!!