If I could go back in time and tell my younger self who discovered poker at the age of 15 years, I would say this:
1. Patience: as in life, everything that is worthy demands a lot of time to be built. With poker this is even more true. Patience, patience, patience is key. When things seem to go wrong, just calm down. Your bankroll will not grow from one day to another. It will take a lot of time.
2. Keep going: it does not matter if you study 15 minutes a day, keep consistency. You are still a teenager, and you can go really far if you don't stop, or if you don't supress your dream even if you need to apply yourself to other things, but poker can remain, just don't eliminate it from your life for any period.