What are some fun things to do together with my boyfriend?

We are both 25 years old. We have been together for 6 years and have lived together for almost 4. I'm afraid we are starting to be that "old married couple" who bickers at each other because we are bored. We still love each other very much, but need some excitment, or at least something better than staying home watching a movie. I'm not a big drinker, so going out to bars all the time also gets old quick. This boring routine that we have is going to ruin our relationship. I just want to have fun with my boyfreind again on day to day basis!! Please help!