You need to experiment endlessly until you get a little hint of momentum, then do everything in your power to make it last as long as possible by not getting distracted.
I'm 37. Instead of regretting that I can't wake up age 18 again, I pretend to myself that I'm 90 and I've woken up age 37 again, and that I get to magically, wonderfully have the next 50 years again.