We're staying at the JW Marriot easter break is there rental bikes around? Is there running room on the beaches(is each hotel beach exclusive?)Want to work out while on trip but Gyms are-BORING.

I've never heard of bicycle rentals, but the beach is huge, and so is the property itself. There is tons of room to jog, even on the main road. Space isn't a problem.
The hotel beaches are all open to the public, and generally this is not a problem. You won't be stopped by anyone if you're running (or walking for that matter) down the long strip of beach known as hotel zone.
Ciao

The main road, Blvd Kukulcan, has a sidewalk that is fine for running (and the people-watching makes it enjoyable). Plus the Blvd has kilometers markings so you know how far you've run.

I'd avoid running on the beach.

Tough place to bike for sure with Blvd Kukulcan and all the traffic. Running on the beach is very difficult due to the soft sand where the beach is flat and the severe grade where the waves wash up. My advice is to walk FAST on the beach (Or do fartleks)and trust me you will get a workout! Have a great time.

You gals were right, bikes suicide but running was a blast running in the beach was a killer gave up after a mile or so and switched to the sidewalk, thanks for the advice.