I was classified gifted as a child but became extremely lazy in puberty with a porn/gaming addiction.

I graduated with a MBA cause it was low effort(lol). I'm really interested in science and math and always have fun when I get into math.

However almost every time I try to start studying/doing math i give up after 15 minutes and start browsing the web while telling myself I'll start tomorrow. This has been going on for a long time now.

How do I finally start?