I've brought my bike inside for the winter, and have it on a cycling trainer.  It's a great way to stay in good biking shape even when the weather outside is frightful, but it's sometimes hard to motivate yourself when riding indoors.  When you're riding outside, you choose how fast you want to ride, but other challenges are presented to you without your choice.  You can't move a hill... you can only go up it.  When riding inside, the challenges you face are the ones you give yourself.  It can be easy, and often tempting, to cop out and go for an easy ride.

That's why I have commercial climbs.  I have my bike parked in front of my TV, and I watch a show while I ride to help the time go by faster.  Then, whenever a commercial comes on, I crank up the resistance on the trainer really high and simulate a climb, and then keep it up until the commercial is over.  It's a great way of working intervals into my workout and improving my climbing skills, and adds a challenge that "you're not in control of" to the ride.

Don't let yourself off easy just because you're inside.