Don't think that this job is the same as any other job you could be doing. Try some other ones. It took me a while to get around to working at small startups, then a large company that runs smoothly with minimal BS, etc.
I suspect that a significant amount of your day energy is lost to the perception that your job is a chore. If you can run your day without emotional judgement perhaps you would have more energy at the end of your day for personal projects. Maybe you could try "going through the motions" that get the job done without the emotional energy expenditure. Or maybe I'm way off base. In any case, it seems that the goal you attained has led to disillusionment. For me the best thing would be working with sharp co-workers where I feel like any day I could be learning something new and interesting that might be useful elsewhere.