Set small goals. THat way the big picture does not overwhelm you, and as you reach your small goals the success will encourage you to keep going. Before you know it, small success after small success will lead to a BIG success!!!
I have found that when I schedule exercise for myself, and not allow myself to think it over I have no problem getting out the door and going to the gym or going for a walk. If I think to long... I think about how hard it will be and the 100 things waiting on my to do list and I don't do it!