For me the worst month was the first, it was getting into new routines and trying to focus on anything but drinking. Someone else said something about every three months feeling kind of blah, and I would agree with that. However, the months kept adding up, and then it was a year, and now I am one month shy of two years sober, and feeling good both physically and mentally.
I also second/third the votes for exercise, if I am feeling in a rut, or in a funky mood getting outside and going for a walk always helps.
Congratulations on five months!!!