Fate provided me the opportunity to begin volunteer Search and Rescue my senior year in college and it became increasingly significant to me for many years, especially 1970-1985, after which my career took me away from Tucson, AZ to Channel Islands National Park, CA.
I learned a lot from volunteer SAR - working productively with others, responding with innovative solutions to unexpected situations, and being ready to respond to all kinds of problems at unexpected times. Our organization was one of the first in the country to admit women to its ranks and reap the benefits. This was in the late 1960s. What I experienced was a more mellow, peaceful, and productive atmosphere when both sexes were present and working. This was news in the early 70s, although well recognized today. SAR is just not for the superbly fit and capable young dudes. In an operation of any complexity, there are many critical roles requiring diverse talents which can be filled by those lacking good outdoor abilities. Also, I met and formed solid relationships with people I would never have encountered otherwise.
The chief benefit I derived from my SAR experience, and this corresponds nicely with the benefits cited by the Mayo Clinic, was that for a very dark three year period in my life, SAR volunteering was about the only positive element in my life (career had hit a wall, marriage was collapsing), but SAR got me through all of that to a much better situation.
Recently, in retirement, I have been working with a local museum, cleaning up fossil specimens delivered as result of field work ("fossil preparation"). Many of the same results, as above, from the time I devote to this pursuit. This has been recently helpful during the current pandemic, since I can perform useful work at home
One other thing, you may receive opportunities not available to others. Channel Islands National Park, like many other organizations, depends heavily upon volunteers for all kinds of jobs - everything from visitor education to eradicating exotic species, but one definite benefit is typically an all expense paid trip to the islands and a chance to see places usually inaccessible to most visitors
It goes without saying that one should choose volunteer opportunities wisely, selecting ones that are of innate interest and concern, but that is achieved, I am confident the rewards will build....
@hikermor thanks for posting this! Over my years with REI, I've participated in a bunch of stewardship events, mostly focused on trail building and maintenance. I love walking trails where I've done work as I often recognized the section of trail and feel a sense of pride in having helped! One of my favorite projects, however, was with our Grand Opening team for our Olympia REI store - where we pulled and removed the equivalent of ~7 football fields of ivy from a local park in the area - that was a very satisfying day!
At REI, we believe a life outdoors is a life well lived.