Thinking about excercising since ages...

I am seriously been thinking about exercising since ages but somehow never ever manage to get it into my routine. How does one really enforce this sort of discipline, I am ashamed that I cannot follow one. I do realize the fact that the more consistent the action is, the more likely for it to be a habit, but I am just not been able to get that consistency in place. Hopefully, once I am done with my studies, will get some time for myself and hence can start my work-outs again.