I would give slightly different advice: sign up for races, but don't compete.
I like having a race booked because it gives me a reason to get out and run even when it's cold and rainy: I want to be ready.
On the other hand, I've stopped caring how I do relative to other people. I go run the race. Sometimes I just run it for fun. Other times I'm working to beat a previous time. But either way, I keep in mind that my main goal is fitness, not victory.
I like having a race booked because it gives me a reason to get out and run even when it's cold and rainy: I want to be ready.
On the other hand, I've stopped caring how I do relative to other people. I go run the race. Sometimes I just run it for fun. Other times I'm working to beat a previous time. But either way, I keep in mind that my main goal is fitness, not victory.