Congratulations on your certification! Since you are new as a trainer and have limited time, I do agree with Karin that employment at a gym is a good idea. Starting your own business takes time (to establish and grow), and does cost some money. Also, it would be very helpful if you found someone who can serve as a mentor for you to show you the ropes and answer questions.
Another avenue for you is employment at the university where you are enrolled. Given the fact that you are an athlete there, studying kinesiology and just got certified, you may inquire if there are any suitable positions there–or perhaps you can make a few connections that way.