Since you're in fitenss and health, I beleive MarketHealth or MoreNiche affiliate programs are what you're looking for. There's also some fitness/health offers on PeerFly, so if you already have an account there, check them out.
Getting them to subscribe to your list is good idea, redirecting them to Amazon is also good idea. Why not use both? First get their email, then redirect them to Amazon offer, later, send them offer for products from one of programs I mentioned above
I highly doubt you'll be able to make anything with 1K+ followers, you'll need a lot more.