Riffle Shuffle Help

My girlfriend and I go to cards with her family and family friends almost every weekend and I am embarssed about not knowing how to shuffle and sick of them having to do it for me. Im the only one who cant.

Ive been trying to riffle shuffle using YouTube tutorials but I feel physically incapable of holding the cards the way the videos suggest and my hands cramp up literally within seconds of trying to shuffle. I feel like an idiot... what do I do?

Edit: Thank you all for your tips and encouragement. I will keep practicing. Im impressed ans humbled at how friendly and helpful this sub is!