In the end, the only thing that matters is how long you stay at it. By how long I mean biographically, like, years, and I also mean how many hours in a day, like from when you get up to when you go to bed. I’ve been at it for an embarrassing number of years, but I still have trouble with the daily part. Fifteen minutes can often seem overwhelming. The problem is, nobody gets to be a professional tennis player on fifteen minutes a day. Forget professional tennis player. Nobody gets a job in a pro shop on fifteen minutes a day.