Crossfit is great if you don't plan on needing your joints for a long life. As Bill DeSimone, author of Congruent Exercise[0], explained in a podcast, "Everyone gets a set of free passes. You decide if you want to use up all your free passes." So don't do needlessly stupid things with your body that wear out your joints any faster than necessary. Your 80 year old self will appreciate not needing a walker. F=ma, it's the law. If you can stimulate the adaptive response in your muscles with no acceleration, why would you ever do anything faster than necessary?

[0] https://www.amazon.com/Congruent-Exercise-Weight-Training-Ea..., "Congruent Exercise: How To Make Weight Training Easier On Your Joints"

[1] https://www.youtube.com/watch?v=j8ZTIvJySiY