well, for what it's worth here's my 2 pennorth:
1) make small changes to diet that you can stick to
2) if exercise ain't fun it's a lot harder to motivate yourself ... i like doing weights cos you get to see results quickly, and mountain biking cos I'm a speed freak
i like running too but that's definitely an acquired taste
3) either get a routine, or someone else to exercise with
4) let us know how you get every few weeks if that helps
good luck dude