While I take some heat in some circles for it, I also do like the idea of having a time goal. Some people say you shouldn't for your first race but you should at least have an idea of what you're capable of and setting a goal gives you incentive to determine what you're capable of, then stick to the plan to get there. If you don't know what you're capable of, how do you know you're not going to get in over your head or sell yourself way short?
Funny thing is I started running to try an lose 10 pounds or so. Now, I'm doing it for enjoyment, and the weight thing is just a bonus.
That's great that you found the enjoyment in running. In doing so, you just greatly increased your chances of both meeting and maintaining your original goal but also living a healthier and, hopefully, happer life. I love it when people state what you just did.