DO NOT TAKE INTERNET ADVICE OR RELY ON INTERNET RESEARCH. Noncompete clauses have significantly different effects in different states and jurisdictions. See a lawyer before signing anything. If the radius/jurisdiction/contacts clauses cross state lines in scope, you may need more than one lawyer. Even if somebody advises that the agreement is not effective, how much personal money can you spend out of pocket to defend a lawsuit brought by the employer if the employer decides to make you a test case? Further, if there is any chance that a future employer may get dragged into the suit, the prospect of remaining with a new employer may be diminished.
If you are being pressured to sign, consider saying that you don’t understand what it means and that you want to get a lawyer to tell you what it means.
I personally would not sign a non-compete agreement unless I was making so much money out of the deal (like in the sale of a business) that it would not matter, or I was planning totally to retire, start a totally new line of work or to relocate to somewhere not covered by the agreement. YMMV
