What got me thinking about clubs is that I joined one last week and participated in it today for the first time. It is a local running club and I joined because I figured it would help with my training. It just seems to be a fact of human nature that when you do things with others, you get better at it than if you try to go it alone. It is no real mystery: More minds focused on problems will come up with more solutions. Also, there is a kind of bench-marking that goes on--when you see how well a thing can be done you will push yourself to approach that level. In an earlier naive state, you would have been happy with your proficiency.
It is not necessarily "all-good" though; small groups are susceptible to group-think and it is easy to fall into alignment with this since the experienced members should and do know more about the subject at hand. One thing easily overlooked is that in the past there may have been a strong, but misguided, personality who got everybody thinking along some line and it hasn't been questioned since then. I should note that I saw no evidence of this today, but these are the kinds of things I try to be aware of.
Today the mission was to go to the Boston Marathon course and run a bit of it. It was a beautiful day and I had a very pleasant run. The nice thing about a group run is that there is always somebody you can run with who is close to the same speed. My pace was pretty good even though I didn't feel as if I pushed myself as hard as usual. Also, I normally take Saturday off and am rested up for the long run on Sunday. Besides this, I ran fast on Friday, which is a habit that comes from the expectation of Saturday off--so I started today already a little sore.