The Fumbling Mindset
Everyone has been on both sides of the fumble. The sooner you come to terms that you will fumble and said fumble will happen at the worst possible time, you will be a better player. One of the biggest things that separates a good player from a great player is how they deal with fumbles, and the best way to deal is to act like nothing has happened.
Do not tap the A button like a mad man. Do not type in chat "lol omg unreal". Act like you have fumbled before. Do not change your strategy. Do not start dropping back for JJs. Continue playing your normal game. The actual fumble isn't the cause of most losses. The real culprit is how that fumble affects your play. Once you stop feeling the rage swell up after a fumble you will understand what I mean.
ROOB
"RUN OUT OF BOUNDS" Everyone says it, but do you really take it to heart? Running out of bounds and to a lesser extent getting tackled as close to out of bounds as possible is one of the most important skills in the game. You may think you do it enough, but you don't. Every time you are tackled in bounds you put yourself at risk and one of the biggest improvements you can make to your game is minimizing that risk at every opportunity. Do not try sick juke movez to get an extra 2 yards. Run the fuck out of bounds every chance you get.
Fumbling More
The opposite of fumbling less is fumbling more, and fumbling more is what you want your opponents to do. You want to tackle your opponent as far away from the sideline as possible as often as you can. GUARD THE SIDELINE WITH YOUR LIFE. Always attack from the bottom. Always give your opponent the opportunity to gain those extra 2 yards with sick juke movez. Every time you force someone to the middle of the field pat yourself on the back, because that's a win in the long term.
ROOB more often. Guard your sideline. Achieve Tecmo Zen.