What works for me is knowing that if I took Mondays off every week, I would likely be let go from the job for being unreliable. But it sounds like you are able to get away with it, so that deterrent doesn't seem to exist for you.

On days when I really don't feel like going in, I just force myself to do my usual morning routine (shower, get dressed, breakfast) and don't allow myself time to stop and think. It's when I allow myself to stop and think that I become more anxious and come up with reasons to stay home. It may sound simple but it has worked for me. I've been at my job for over 4 months and have only called in sick once. Much better than my attendance history at previous jobs. Good luck!