Hint #1: Planet Fitness isn't in the grid but see if you can find some other well-known gyms (if you live outside the US or in a small town, some Googling will be needed)
Hint #2: There are a few clues that start with the exact same word
Hint #3: Take the title literally... 5 times
Hint #4: The letters of interest are where the gyms and the entries with the "Hit" clues intersect
Hint #5: The gyms are Equinox, Crunch, Blink, Curves, and Gold's