Searching for image related to fitness or being active

Hi elearning gurus, I am creating a compliance activity that educates educational trainers about the professional competencies they need to prove in order to remain as "active" trainers. 

I am inspired by David's  How to Build a Simple Elearning Game, which uses the wonderful graphic below.  The travel theme doesn't work for my project, but the path/journey concept and the clickable buttons do.  

For this project I want to link the idea of  being "an active trainer" with fitness, and have been searching for a suitable free or low cost background (but high quality) image of a path/journey which could be related to fitness, or a race track, running track, or even the interior of a gym.

I have not found anything suitable.  Any ideas on where to look for some suitable images?