What you're talking about doing is what we call making a radical career change. It isn't always the easier thing to do but many, many people do it (our experience with thousands of job hunters suggests that most people not only make one radical career change in their lives, but two to three). We call it radical because not only are you changing job titles (functions, tasks, responsibilities) but are also changing the field or industry in which you wish to work.
We applaud your desire to try to make this kind of change. You sound like someone who plans ahead and doesn't just jump willy-nilly into the fray. That's best when undertaking this kind of career switch, although some take the plunge and never look back!
We think you're right to try out a couple of courses in journalism, while still employed at your current job. This will allow you to test the waters, so to speak, and see if you really like writing in a "journalist" fashion. You'll learn some basics, become familiar with the "jargon" and meet with others who are trying to travel the same path (it's usually reaffirming to know that you aren't the only one who wants to try this!). Then if you like the classes, you can pursue further education in this field if you feel it is warranted.
Now for experience — since you say you write a great deal already, switch the focus of your writing to sports in your non-work time (weekends are full of local sports events, if your community is anything like ours). Begin to write some articles on this local sports scene or even follow a national team and write about them. Pretend you have an assignment from a local paper to write these articles and see how you do. After you have written a few, share them with friends for their feedback. When you feel ready, if you know any local sports "celebrities" (this could include the high school star quarterback) ask them to do an interview with you.
In time, approach a local paper (many communities have some kind of "neighborhood" paper) and show the editor your work and see if you can get some kind of assignment. Volunteer to do this if you don't feel ready yet to ask for money. You can try approaching the sports internet sites as well, as they are often looking for writers, but you'll probably need some established experience to get in the door with most.
Finally, don't overlook how this job will fit your personality and personal traits. It will involve lots of deadlines; you'll have to be resourceful in ferreting out information and know how and where to find that information fast and accurately. You will have to be able to write so that your readers will easily understand what you say. You'll need to be able to convey your opinions and thoughts in a way that can affect how people think about certain issues and topics. You'll need to be prepared to make less money as you start this career — only a few ever make the really big bucks, so don't count on that from the start. If after considering these kinds of things you still feel the excitement about this new career, go for it. Best wishes to you.