It depends on what kind of no-compete clause it is... To be sure what EXACTLY yours means, have a local lawyer look at it. It should state exactly what you may and may not do.
For employees working for a company, usually they're imposed if you've received some kind of special skill or knowledge, or if you have had access to the clients, or have gotten some kind of potential unfair advantage from your job, to be able to do whatever the job is on your own, or where it would be easy to take business or customers with you to a new job. Real estate agents, architects, hair stylists, plumbers, etc might be asked to sign one.
Small businesses when sold as a working company, such as our horse rehab hospital when my wife bought it, are another time when a no-compete clause is put up. Our broker made the seller sign a no-compete clause stating that she would not take with her any clients, and would not partake in the startup of any other horse rehab facility within 50 miles of this one. This doesn't mean she couldn't have gone and bought another one already existing; she just couldn't build a new one "in the next block".
In a commercial building rental agreement, the tenants might have one built-into the lease, promising that no similar business will be allowed to lease space in the same building, and many cities prohibit competing businesses from being with (x) feet of each other.
Charles