Try to take the attitude rejections are all part of the business. See acceptances as bonuses and remember you can always rework your rejections.
Equally there may be nothing wrong with your story to cause the rejection, it might be the judges/editors just preferred another tale, due to taste, the other one fitting in better and so on. The great thing is to remember it means you can send the story elsewhere instead!
Can you show your commitment? That is can you show you take out subscriptions to the professional mags, regularly read editoral and publishing blogs, you regularly enter writing competitions and ideally have had one or two things at least published.
Enjoying your writing is crucial as if you don't nobody else will.