I'll be a senior in college starting in the fall and I've run Cross Country and Track since freshman year of high school. Currently I'm doing 80-85 miles per week in preparation for cross country (I'll peak at around 90 in a couple of weeks). I've had the benefit of having 4 different coaches and lots of teammates to get a lot of different approaches to training.
There are TONS of training plans online for all levels of runners. You'll especially see a lot geared specifically towards beginners or complete newcomers (I like coolrunning's site for these kinds of plans http://www.coolrunning.com/engine/2/2_4/
There are definitely pros and cons to following really structured training plans. Some pros would be: easier to set goals with regular scheduled workouts and races, don't have to think too much about training on a day to day basis, gives you a good idea of how to approach training. Cons would be: not very much flexibility, can be overwhelming, etc.
I have raced distances from 800 meters through half marathon, and plan to do full marathons once I graduate. Once you start to get into decent running shape, races are a blast. There are few experiences I've had that can match the amount of adrenaline and competitiveness I feel when racing.
Even though I truly love running, there are days where I am not super motivated to go out and do it. In 99% of these cases once I can convince myself to start running, then I'm happy to be doing it, so a piece of advice would be to not convince yourself that you don't want to run before giving it a mile or two to actually see if you want to run or not.
If you would like a more specific plan (types of workouts, how much mileage, what kinds of cross training you can do) to help you on your way I would be happy to oblige.