"I had to succeed because I was running out of ways to fail. I had to keep going!" Thomas Edison
The more you do something the easier and the better you will get at it. The same goes for exercising. There are some days where the hardest part is just getting to class, or the gym, but once I'm there I am ready to teach/exercise and feel amazing once I'm done.
Those who say that they will succeed do, so it is your choice! If you want something bad enough, then you have to work for it.