Great tips, most of which I've always done. Jamming with myself and/or adding a drum loop and playing a long is usually the way every song I have starts. The problem is, I'm not good at programming drums, so if I start an idea from jamming with a drum loop, I usually get lazy, loop that same loop and vary the vocals/guitars, then find another loop for a bridge/chorus/etc. Needless to say, all the loop usage really takes the energy out of a finished song :/
I'm also employing the 'listening to other artists' idea. Not to come up with different musical ideas, per se, but rather to come up with different structural ideas. I find myself sometimes getting stuck in verse/chorus/verse/bridge/chorus or otherwise restricted structures, when in general, songs have fills and little breaks and subtle changes all the time.
Nice idea from Alex above, I might give that a go. It's true, I usually walk to the tempo of whatever song I'm listening to. Needless to say, this sometimes complicates mounting stairs when the tempo is high