How in the HECK do I get back in Shape

I have been slipping further and further into a state of unhealth. When I was in highschool I used to run Cross Country and it kept me bone thin. Never drank soda, never ate carbs except on the night before a big race. After high school, I went straight into boot camp, where I actually gained weight (muscle) and got out of boot camp weighing in at a fierce 145 lbs. at 6 foot 1 inch, that is pretty skinny. 3 and a half years later when I got out of the Marine Corps. I had only gained 20 lbs.
But in the period of the last six years I have ballooned steadily upwards to 250. Now I know that the numbers aren't what is really important. But I still use it as a gauge since I feel tired just going up my stairs at home. With my busy schedule, and my work where I just sit all day in front of a computer, I have had a hard time burning the fat, and building my endurance back up. I love running, I hate wieghts. I love hiking, swimming, walking, inline skating, and biking. But just have not been able to work out a routine that includes excersice. I might have to wait until this current project at work is done and then implement some new routine at the begenning of the next project. At any rate, that is what is up for me this morning.