When a fight goes to the ground and your opponent is on top of you, you should never, never, never end up on your stomach. Being stuck in that position causes all kinds of problems. It exposes the back of your head and your neck, it keeps you from being able to see or predict your opponent's actions and, worst of all, it makes it impossible for you to defend yourself or react in any way to what's going on.
Instead of rolling onto your stomach, you should turn your body so that you're either on your back or on your side. You should face your opponent dead on. Not only can you see him now, but you can also protect yourself and find ways to turn the situation around. In general, on your back you have more control and more options.
Of course, rolling onto your stomach might be easier and might even seem like an instinctual thing to do...but it doesn't help you. It only leaves you exposed and vulnerable to attack.
I think it's important to face up to the things that take us to the ground in life, as well. It's a scary thing having to face an opponent that has the obvious advantage of being on top. Acknowledging that there's someone on top of you means that you have to fight; that you have to trap a foot and an arm and exert the energy it takes to turn the situation around. Sometimes that's hard to do because we don't feel like we have the energy...or maybe we're just afraid of the guy on top and we don't want to have to look and acknowledge that he's there.
But the alternative is to leave ourselves exposed and in a position where we can get hurt. And that's not really an option. It takes courage, I've found, to choose to look at your attacker just like it takes courage to face up to a problem that is holding you down. But we all have that kind of courage inside of us. It's hard to harness sometimes, but if there's one thing that I've learned from training it's that we often have to do hard things--things that are uncomfortable, painful, and even downright scary.
That's martial arts...and the only way to improve is to practice those hard, uncomfortable, painful, scary things. In the long run, we're training to be better people through and through, and that journey makes doing hard things worth it.
In life, we're training to be better people, too, hopefully. It's hard to have the courage and wisdom to stare your problems in the face and tackle them head-on, but it's better to have some control while lying on your back and facing your attacker than to have no control while blind and exposed. We want to always have options. Facing up to your problems gives you more options than denying them or running from them ever will.