https://www.youtube.com/watch?v=eBl3U-T5Nvk - Cellular Respiration Overview 

https://www.khanacademy.org/science/high-school-biology/hs-energy-and-transport/hs-cellular-respiration/v/introduction-to-cellular-respiration - Introduction 

https://www.youtube.com/watch?v=00jbG_cfGuQ - Crash Course 

https://www.carman.k12.mi.us/Page/6258 - How Exercise Affects Repiration