I second this! The times in my life when I've felt the most productive and engaged, I've been part of a tight group with similar goals and interests. Don't underestimate the degree to which people are fueled by outside interactions, not for external rewards but simply because of the shared momentum. The lack of such a peer group one of the things I've found the hardest after moving to the US, perhaps because the academic moving around makes it hard to build long-term friendships, and quite likely also because I'm not very good at it.