Why do I have dreams where I am falling, so realistic that I physically try to stop myself?

No one really knows the answer to that. I myself have those dreams and I can't figure them out at all. Have you consider reading a book on dream interpretation. It might give you some insight.

Psychological fact: when the brain falls asleep too fast, it panics and thinks you are dying. So if you have a falling dream and you shoot up, you were most likely falling asleep too fast and your brain shocked you awake.

Dreams are directly connected with your subconscious mind, and they often reflect experiences or feelings that you try to process. If the dream is recurring that propably means that you struggle with something for a longer time. It's hard to say what it could mean in general, but you could look into some possible meanings and normally you should feel which one applies to you.

It's normal,dreams have meanings.I maybe correct,but there's something in your life you're worried about.Based on my memory.

Normally when you are asleep your brain paralyzes your body so you can move while asleep. But if you have something causing you a lot stress or a sudden stimulus then your body can react.

WHY you have these dreams is not currently confirmable, but they could reference you not having control over your own life.

Sometimes before our bodies are fully switched off as you may say we can still dream. You're body is paralyzed when dreaming but can move if you are woken up. No one really knows how you can physically stop themselves in a dream. It is just out of instinct. Dreaming of falling can be triggered by stressed or overtired. Our brain enters into sleep cycles more aggressively but our bodies haven't quite caught up. Insecurities or anxiety an also trigger the dream of falling. I will admit i've never heard of someone trying to physically try stop it in a dream