motivation

I'm pretty upset with myself... I have YET to go to this new gym where I bought a membership a month ago. I really do want to work out but every night I get home from work and have no motivation to get back in my car, drive downtown to the gym etc... where can I find this motivation? I need some.
I really do want & need a bike. I may be going to the Bike Collective on Tuesday, but I would really like a bike sooner than that. I might go to wallyworld and just pick up a cruiser for $100 tonight after work. I think having a bike will be motivating for me~ I'd much rather ride my bike around the city than get in my car and spend MORE money on gas!