If we do the same motion over and over again, two things happen:
1. Imbalances develop from overuse.
2. The musculoskeletal system adapts, and your strength, flexibility, and endurance plateau.
Thankfully, there's a pretty easy solution -- switch things up! Now, this could be something as simple as trying something new. Instead of biking, go for a swim. Instead of running, go for a bike ride. However, you can also just change the kinds of motion you're doing during your activity. For example, if you're a weightlifter who likes to go hard and heavy, maybe try a session of low weights and high repetitions. If you usually play goalie in your pickup hockey games, why not give another position a try for a week.
When we stimulate our musculoskeletal system in new ways, the body is forced to adapt. So whatever you do, just keep your body guessing!