Will a non-compete clause hold up when switching low level positions, < $10. I was a personal trainer at on gym and moved to another gym last year.

I've been threatened with a law suit by my ex-employer. I signed a non-compete agreement when I was hired in July 2014. I left that gym in Oct 2015 and have since been working at another facility. I've received a letter from my ex-employer's attorney stating I must quit my current job or they will continue with a law suit.