gwyneth,
don't be so hard on yourself, i like you used to find it impossible to make myself "work-out". i smoked for 30 years, which somehow always seemed like reason enough to not exercise!! crazy.

it has taken a long time for me to develop healthier habits. but, it evolved pretty naturally. first with daily dog walks, now, after 13 years of that i have firmly made the connection that when i get out for a 40 minute or longer walk i really do feel better. because of my lifelong battle with depression, feeling consistently better is quite motivating. also, now that i am in my 50's i am also motivated to keep my muscle tone and stamina up so that i can enjoy the activities and sports that i love. so, now i actually do exercise in addition to walking, and i am finding that i enjoy it! i have to add though that i wish i had started this earlier, as now i have some minor physical limits that i wouldn't have had at a younger age. ah well, isn't hindsight wonderful?
i say, just find something that you really like to do, don't make it a chore, and it will be much easier to stay with it.
best of luck with this!
path
ps. as a daily drinker, i never have had problems with hangovers, so i didn't have that impediment. once i lost the cigarettes for good i felt much better mentally and physically.