Just do it!
I haven't been out for a run for a week, because my lower back has been playing up, aching when I bend forward. I have spent some time on my bike instead during the week, but today I went out for a jog again. It felt soooo good. I was a happy bunny when I came back home! Running is just such a kick, and it releases so many endorfines, you just can't feel anything but happy afterwards ;)