I am 43 now. The last 10 years of my life have been equal parts challenging and amazing. I have a little girl who is about to turn 5. My teenager is about to turn 18. I've made more "progress" and done more growing and experienced more in the last 10 years, than in all the years before.
Whether or not you have kids, I would do your best to learn how to enjoy each day. But learn. Whatever you do... keep learning.
Contrary to popular thought, you don't have to be young for great things to happen. They happen all around you, all the time.
Also, there's an author by the name of James Altucher and he's written some things about just being a little bit better, a little more improved than the day before. His stuff is good. I'd recommend it. Also, Deep Work by Cal Newport.
Thank you for letting me share my thoughts. I'd be happy to talk more if you ever want to.