So, yes, I actually volunteered to end up in prone in a puddle doing paint scraping. Backstory -- I'd wanted to volunteer with Habitat for Humanity for a long time, and had finally signed up for a work day.
Haven't heard of Habitat? They build and finance homes for deserving, hardworking lower-income families looking to help build and own their own home. They leverage volunteer forces for almost ALL construction labor. I think the idea was to keep down costs, but it has also raised an amazing, cheerful and incredibly skilled and dedicated volunteer construction crew that welcomes new homeowners in to a community unified by purpose and pride in their work.
Now you might ask what this has to do with climate action--but I say, "everything!"
In a previous blog post, I outlined an idea of a low-carbon luxury lifestyle, where extra $$$ go to "experiences instead of expendables," as we said in our corny company holiday card this year.

And while hiring people for their skills is lower-carbon than buying "stuff" and provides local jobs, it does not speak to the idea at the heart of the cultural shift that is slowly spreading like a comforting sip of hot tea through the empowered climate action community: it's about something more than yourself.
Hiring a trainer and taking classes and soaking yourself in arts and ambiance are all well and good. But as researcher after TED talk after grandmother can tell you, the happiness return on doing something for yourself rarely compares to that of putting forth effort to accomplish something meaningful that positively and visibly impacts the lives of others.
Scoff at "selfish altruism" or societal approval if you will -- but honestly if someone devotes time and effort to doing something good and worthwhile and they feel happy, who begrudges them that reward? I'm pretty sure feeling good about yourself has zero carbon footprint.
And one of the greatest things about volunteering is what it isn't. For once you're not buying anything. You can vote with your time and intention and effort instead of just your dollars. Especially if you use transit, bike, carpool or walk to your volunteer destination, I'd say it's one of the greenest and most worthwhile things you can do with your weekend (aside from swing dance lessons, but that may be my own personal bias).
Plus the range of new and fun experiences you can add to your usual weekends are endless. So far I've been treated to a gala and dancing at a charity benefit, enjoyed amazing live jazz at a community festival, and found myself on an all-women volunteer construction crew listening to Celene Dion and Abba in between power tools and hammers in the skilled and capable hands of the ladies I'd like to dub the "Golden Girls of Construction." Now I just need to see elephants fly.

So if you're looking for new, interesting, meaningful, worthwhile, fun, green things to do I highly recommend volunteering.
Great resource -- volunteermatch.org - it's like a job listing site but it's ALL volunteer opps, mostly one-day things and so far my experiences have been awesome.