So hard to find a volunteer opportunity for full-time employees

I have been wanting to volunteer for a long time but I seem to spend my entire weekend just looking for one and still end up empty handed. I feel my biggest obstacle is that I am a full-time employee (FTE) and just searching for something to do in the evening or over the weekend.

Majority of opportunities found on sites are for full-time volunteers, so all of these are instantly struck out because there is no way that can fit into my schedule.

The second obstacle is that my job also have last minute assignments for any given evening or weekend of the week. This means that I cannot commit to something that is down the road or require recurring attendance.

Basically the remainder of the opportunities full under that category, so what does that leave me? There are some rare ones that require certain certificates. Even soup kitchens now require sign-ups and fill up.

Perhaps I am looking in the wrong places, or perhaps using incorrect keywords. This really should not be harder than finding a paid job.

Future Reading - New Ways to Think of Volunteering/Philanthropy

I like some of these thoughts of long term philanthropy.

http://ideas.ted.com/2014/07/07/rethink-the-way-we-run-charities-a-useful-reading-list/