Ok thats cool. Try to get into as good of shape as possible as soon as you can. With you being 12 years old, its probably a little too soon for you to start seriously lifting weights, but you could still do basic things like pushups/sit-ups.

I hope you still want to be a SEAL when you're 18. But don't completely rule out college. In order to be a Navy SEAL, you still have to be smart, and having the extra time to train that college would give you will be very helpful.

Good luck!