Well, more often than not, I find that the problem of motivation isn't wanting to do something bad enough, it's usually just feeling overwhelmed by the whole task in front of you.
Let me use your desires as an example:
-get my body into shape, i.e. lose body fat, gain muscle, and have better endurance
For this one, getting your whole body into shape usually means setting up a permanent full body exercise routine. Well, that's good, but that isn't where to start... that's your final goal.
To start with this one, how about work on your basic endurance first. Let's say (for purpose of example only, since I have no idea how fit you are already) that you can only walk one mile at a time, and at the end of that mile, you are exhausted. Work on just making it to the end of that mile for a month, and work on nothing else. Once you can walk a mile without getting overly out of breath, lengthen it to a mile and a half... then two miles... then take a whole hour to walk four miles each morning before your shower. Start with one exercise that you know that you can do, then push yourself from there. When working on your arms, find out how many push-ups you can do, or how much weight you can lift easily, then work up from there. Count how many sit-ups/crunches you can do in one sitting... One step at a time.
-eat better, i.e. more vegetarian diet, less junk food
Cut one item out of your menu at a time... First, cut all of the candy out... then cut cake out, then increase your vegetable intake... Stop eating hamburgers, then steaks, then chicken and pork... Start changing your tastes so that you enjoy vegetables more often... Just replace one food item at a time.
-go to grad school (econ/public admin and policy)
One semester at a time...
-learn a new language (french)
Forget about French... It's a pansy language.
(Okay, just kidding... I'm just playing on good ol' American stereotypes.)
I had some success with learning German using a set of language CDs created by Pimsler (or something like that)... Just go down and buy some CD's, then take it one lesson at a time. After you are done with those lessons, find other lessons, or find a school/tutor and take it one lesson, one conjugation at a time.
Does that help to put an easier perspective on achieving your goals?