Stumpy - i don't know if this works for everyone, but i've found that i can talk myself into believing things. If you spend the next couple of days with a post it note stuck on the edge of your computer (or some other highly visible place if you don't work at a computer) saying something like 'i love running, i can't wait to get out there and hit the road' then after a few days you'll be believing yourself. especially if you repeat it to yourself regularly as well as just reading it.
just a thought. works for me for things i hate, like ironing. persuade yourself that it's actually more fun to do it than to not, and you'll be looking forward to it.
My general theory for life is very simple - if something's not fun enough as it is, alter it slightly until you really do enjoy it. i do the ironing in front of the tv watching a good film now, or the friday night sitcoms. i dont have suggestions as to how you do it, as i dont know what works for you, but try spicing up your run a bit, and see what happens.
Happiness, like life, is self service. no-one's going to hand it to you on a plate, so go out there and make it happen.
good luck, sweetie, i'm sure it'll come right soon.
Pamela x