Their posters covered your bedroom walls, and you would snap up any magazine that had an article. The time spent replaying the YouTube clips, and a quick check of your phone background is further evidence that these people inspire you. The first guy to catch my imagination was Lou Ferrigno as the Incredible Hulk; I couldn't imagine that a real man was that size.
Jordan's dunks, Pele's footwork, Tiger's golf, Ali's blurring speed, Tony's skateboarding, Venus and Serena's tennis, Babe's home runs, or Jerry's gridiron speed. These are many of the first faces that come to mind as we reflect on those that have spent the required thousands of hours to become experts in their craft and hone their bodies to achieve astounding results.
Much closer to home people that are doing amazing physical feats each day, much closer to home. Ask, the marathon running co-worker how training is progressing toward her next race, the wounded warrior about his next Crossfit Fran PR, or the neighbor about her yoga pose proficiency. Check with the guy at church, about his next Brazilian Jiu-Jitsu belt test, or the beast with python arms buying baby diapers in the checkout line ahead of you.
Sports Illustrated covers and Wheaties boxes are great places to start looking for inspiration, but don't limit your sources. The face time with these local examples will give your physical preparations a shot of inspiration, and besides, they probably won't charge for an autograph. Ask questions, deliver encouragement, and always bring a Sharpie.
Going Further: What are the world famous names that have had an impact on your physical training? Who are the locals that have inspired your training? Have you ever interacted with them and expressed your admiration? How did that come about? Who can you learn from locally?
Writing soundtrack: crickets, not the band. You know, the chirpy critters that come out at night.