Where to find video examples of workout exercises for my fitness app?

Hi hackers!💥

I make a fitness app for mobile devices and I have a small problem.
I want to show video examples of exercises but I don't have a budget for making my own.

Does anyone know where I can buy them (or get them free?). I try to find them on photo stocks but with no result.

Also as an alternative solution, I'm looking for ready-made 3d models of a person with animation of exercises.