According to a recent study, working out in a group makes you happier than working out on your own, it actually increases endorphin levels.
That may be so, but for me, it completely depends on my mood. Sometimes, I enjoy having someone to chat with while I run. Other times, I want that time all to myself (we all know how far and few between those are).
What about you? Do you like working out with someone or do you prefer to be by yourself?