I was a young leader in Guides as a teen, and later an assistant leader with a Venture Scout troupe while in Uni, but basically gave up volunteering for quite a few years once I got into work, building career, travelling lots, newly married and getting house sorted etc.
I took on voluntary roles at work though once I settled in - things like Floor Marshall for emergencies/fire evacuations, and re-did my first aid to be an occupational first aider. I mentor as well, and have offered my skills to coach many people before interviews etc.
As DD grew older, I have gotten back into a few things outside work as well. While I never became class rep for school or joined the PTA or Management Committee etc, I have always (up until the last 2 fairs) done a "shift" on our class's stall at the summer and winter fairs (lots don't), and helped on our class's turn arranging the monthly coffee morning through the PTA. I've baked numerous buns and cakes for fairs and also for the annual tea hosted by 3rd class catholic instruction parents for the 2nd class DCs and their families after first holy communion (multidenominational school so that is a separate thing). I was part of the team when DD was in 3rd class for that tea, and again last year as they were a bit short in 3rd, I'll probably do it again as a washer-upper this year too as I live very close to school.
Last year, I joined the Catholic Instruction Committee, which organizes all the catholic instruction classes (in school building but after school finishes, using separate teachers which the Committee employs, and doing all the admin), and the 2 sacrament years (First Holy Communion and Confirmation). This year, and probably next as well, I am secretary of the Committee so that is quite an amount of paperwork to look after as we have roughly 100 DCs enrolled in CI.
The other thing I have done in school is, while I work too far away to assist with most outings, I have gone in and given a talk about the Government and Civil Service to the Student Council (both 4th Classes) before their visit to our Parliament when DD was in 4th. The Parliament visit is an annual thing for Student Council and I was able to be an extra helper on the day as I work close by - just not for the bus. School are always looking for parents to do things like this - talk about their work or hobbies or things that would interest the DCs, especially if they can relate to the curriculum in some way (and most can!).
I had also volunteered to be a Cub Scout leader when DD was eligible to join the local troupe. I have experience messing about in boats that was useful to them (sea scouts), and my previous scouting experience too. After just over a year as assistant leader, my civil service background apparently shone through as an organized and paperwork person, and the current Section Leader asked if I would take over so he could step back to assistant leader (after 10 years!) - so that is another big commitment.
While I have not formally signed up as coach etc with other clubs that DD is involved in over the years, (some need lots of parental involvement, others want none), both DH and I have done lots of being a "parent on the ditch" keeping an eye for ones who need a break and not wander off, running for balls, finding water bottles or first aid kits etc, we take our turn when sailing needs parents "on deck" with radios while the kids are on the water with coaches, we generally have been among the group who put up and pull down goals, move trollies with boats in and out of water, scoop up all the hockey balls at the end of a session etc - rather than just drop or scoop and run with our DC. Some have involved getting Garda vetting (similar to CDB(sp?) checking in the UK).
I enjoy almost everything I do in this vein. Sometimes I do it to support others - like school - but other times I do it as much for my own enjoyment. I am loving messing about in boats again, and Cubs age are lovely as they still respect you generally, and I have gotten back into camping purely because I had to with Cubs, but have now bought my own tent and gear to go off with DD on girlie adventures (DH has given up on camping as he thinks he's too old!). And I am learning from everything I do - how to work in groups, diplomacy skills, different ways groups can work but all still effectively, management skills, accounting skills, communication skills, how to deal with difficult people, lots of skills which are readily transferable to other aspects of life and particularly to work! And I am also getting an opportunity to get trained myself in some fun skills like powerboating, sailing and adventure sports without having to pay for this.