Impossible. I don't know how long a blitzball game is, but I'm going to assume 10 minutes. If you lost millions (I'll assume 3 since that is probably the lowest plural number of million referenced by "millions") of games that are 10 minutes long, that would have taken you 8,333 hours and 20 minutes--which allows a year of playing with 70 minutes of eat, sleep, restroom break per day.

What is it they say about silence being golden?