When I was younger (tweens & early teens) I would look at the skinny, toned girls in my class and think...next time I'll look like them. As in, next lifetime. Talk about disordered thinking...
Honestly, to me YOLO means drunken college kids making stupid decisions. lol. I think your new version is much better.
We get one body and we should treat it well. Sometimes that means enjoying a second helping, but more often is means celebrating acts of moderation.
I struggle a lot with motivation. I think having a mantra is a wonderful idea!