I'm only in my late 20's and I feel so unhappy with that age...I seem to see younger people around me constantly and I also feel like I might have wasted parts of my life ad it bothers me to no end.
I've also had some really bad OCD about death and dying but that's for another thread...
Living in the now doesn't help? Hmm...have you tried really, really immersing yourself in a book, movie, or video game? That always helps me. So does music. If lyrics in music trigger you then just listen to instrumental stuff. Try keeping a notebook and writing down the thoughts that make you feel bad, and then either tearing it up or reminding yourself that they're just thoughts due to your OCD and you can't let it control your life...that has helped me.
Hugs for you.