I just started running again this past week. I am trying to run minimum 5k-10k about 5 times a week. Running completely blows compared to cycling in almost every aspect. Really the best plus to running, is you can do it anytime, anywhere and all you need are your shoes. But I am hoping to never have to feel that pain in my legs the first 3 days after my first 2 runs. (I haven't run since high school like 12-13 years ago) I do feel as though it helps me keep motivated on the bicycle more and certainly helps me feel better while pedaling.