Your mind is an incredible tool. Don’t let it go to waste by never using it. Some of the most clever things have been totally fabricated with the mind, and that’s something almost no one can disprove.
The body is the key to improv. Don’t let it go to waste by never using it. Once you ground yourself in a character and use your body to proliferate that character, your scene is headed straight for greatness.
What I’m saying is, develop both so you can do both. Saying “get out of your head” is very very good advice, but if you never access your wonderfully well organized mind to fuel a character, your scenes are eventually going to get repetitive.