Resolving new life directions with old habits

What do I do when half of me wants to dive into yoga and health and meditation while the other half is still clinging to the easy, normal way of living? I don’t know how to become what I know I can be when there is still something holding me in the college mindset. I’m 29, so I still like to go out with friends on the surface, but while I’m out drinking I always realize that it’s not making me happy and I never have as much fun as I thought I would. To me, it seems it’s got to be one or the other – grow up and become a serious, spiritual person or give up and stay where I am… How can I marry the two sides of myself?