Many people comment that my left hand is very active when I play pickleball. I'm right handed, so this means my non-hitting hand is always moving, even though it's not even gripping the paddle.
This is an old habit from tennis but it's actually a useful tool in pickleball as well. Many people's left hand (could be your right if you're left-handed) looks like a dead limb, just sort of hanging there but not serving any useful purpose.
Instead, your other hand should act as a counter balance, giving you greater strength and stability when you play. When you wind up for a forehand, try putting your other hand in front of you. This makes it easier to use your whole body instead of just the paddle arm when you swing.
Similarly on the backhand, keep the other hand up when preparing your shot. This will give you better balance and strength as you use your whole body instead of just one arm. And other overhead, as soon as you see the opponents hit a lob, put the other hand up in the air (in tennis we were always told to point at the ball). This gets your shoulders up and turned sideways, again allowing us to use our entire body when swinging.
Replace your paddle with where your non-paddle hand was and whack, you have a great overhead!