What can I do to inspire more participation in our Co-op Barn’s activities?

Our barn is run as a co-op and we host annual spring/fall clean up days (among other activities). Despite there being over 40+ people in the community - we only get about 1/3 participation or less - outside of our holiday party where we probably get around 50%.

Our clean up days usually include landscaping projects, moving/painting jumps, deep cleaning the barn and tack room, etc. as well as a potluck lunch.

Looking for ideas to help encourage more of our community to participate - there’s a core group that always shows up - those doing work shifts and such - but want to target the people who only take one lesson a week, or lease a horse one day a week. Not necessarily because we need more people to do work, just to really build connections in the community. We are an all adult community but also all of us are crazy horse girls and some have young kids so it doesn’t need to be adult-centered.

Any thoughts??