Before I get too many people reacting that they don't want to serve a mission - there are a boatload of options.
Sure - you could go proselyte for 18 months. But there is so much more. I know someone teaching classes at BYU-Hawaii for his mission service. A neighbor was a tour guide for the summer at Cove Fort, another worked at a girl's camp - didn't have to be there every day, but checked in on them.
I've got a neighbor who works at the institute for his mission. My aunt and uncle worked in the JSM building helping people learn about family history, my wife's aunt and uncle drove around Nevada in their RV collecting old birth and death data. I've got a current neighbor who is a leadership mentor in SLC (living in their own home) who meets with and trains new ward leaders in Rose Park - helping new leaders in a low income area. Another neighbor lives at home and helps one of the SLC missions in their office.
My old YM leader and his wife works at welfare square, assisting with service projects people do there. Another neighbor was a case manager, of sorts, with low income families - helping connect them to services and get on their feet.
I'm not saying it's for everyone - just that you have to reset your expectation of what it is to be a "missionary". There are a ton of options - many of which are only for a couple of days a week and that you can do while living at home.