Fifteen minutes a day for a year is more than 90 hours. People have learned whole instruments in less.

Small amounts of time get dismissed because they feel like nothing in the moment. Fifteen minutes cannot produce anything visible today, so the mind files it as pointless, and the arithmetic over a year is never actually done. The total is large enough to change what you are capable of.

Choose one thing and give it a quarter of an hour daily, at a fixed time so it does not need deciding. Accept that the first month will show you almost nothing. Then keep going anyway, because the interesting part is further out than you can see from here.