in the long run flat betting each game is the best thing to do, helps you from getting caught up in the moment or thinking this is the game of the yr, only to have it flop. Maybe allow yourself one bigger bet a week to kill off the urge of always going big.
I find it extremely helpful to move my winnings from my Sports account to my Casino account. Have, say, 90% of your bankroll in your Casino account (provided that you don't play the casino games) and 10% of your bankroll in the Sports account. Most Sportsbooks you open an account with will provide you with both a Sports and Casino account. That way you only see a small portion of your money in your sports screen. I have a bad habit of going all in so this method has helped.