I've come to the realisation that it's always going be a struggle to pick it up after a missed day, and that's fine. Sometimes you miss. The important part is that you're doing something. I've gone to the gym on and off for several years now, my longest streak was five months, with twice a week. Sometimes I don't go for two weeks, sometimes I just do it once, or do it twice and don't put that much effort in, and that's FINE! Remember that. It's okay to miss a day, even though it ruins a "streak". Just pick it up again. Easier said than done, I know, but letting yourself fail, and not feeling all the worlds dread and failure because you didn't go to the gym today is kind of nice!