My wife and I own a gym (in addition to our full-time jobs) that has several salaried trainers on staff. They sign a non-compete that for 1 year from the date of termination, they cannot take a trainer job at any gym within a 5 mile radius from our location, and they cannot own more than 20% of any gym located within a 10 mile radius.
This prevents them from opening up shop across the street and taking half the clients with them. It prevents them from doing the same with a nearby competitor.
It is limited by time, has a specific geographic area, and is only for a specific job. They can do whatever they want beyond a 10 mile radius on day 1, or they can open up a gym on day 366 anywhere in the world.
We've never had to litigate it because it's never come up, and if someone wasn't happy and really wanted to get a job at a Gold's two miles down the road, we would probably let them provided they didn't spend their last week giving our clients their new business cards or something.