This was asked recently by someone whose opinion is important to me so I thought I'd dedicate a post to the subject. It's really not a cut and dried answer though. I didn't wake up one morning filled with zeal to be green. It was a much more gradual change of viewpoint, mindset and awareness.
I started with the easy changes like most do; recycling. The more I thought about the whole footprint thing, the more decisions became important: growing/buying locally, reducing what I send to the landfill, water conservation, renewable energy, cutting back on electric usage. One step naturally led to another so when appliances broke down I looked for energy star (high efficiency) models to replace them. When I got serious about what went into the garbage and growing more vegetables composting was the obvious solution (and one of the most satisfying changes I've made). Environmentally, the footprint is the key motivator for me; it's become a personal challenge or test to see how well I can do, but I think a big part of what pushes me is my innate pessimism.
What if? What if it all goes horribly wrong? If we've learned anything this past year it's that our economy is a fragile construct and is terribly vulnerable. We also know it's going to get worse before it gets better; what if it doesn't improve? What if? The climate, government, natural disasters, epidemic (natural or engineered), alien invasion (hey, anyone would get jumpy after reading the Posleen books!). My emotional reaction to worst case scenarios is to want to gather my loved ones close around and keep us all safe (much easier if all were on the same continent!). My practical side wants to be better prepared. Not in the build a bomb shelter and stockpile beans and bullets sense, but in having the knowledge and tools to be as self-sufficient as possible.
This desire is what has driven me to learn the basics of food preserving, butchering, knitting. It's why I'm trying to convince my parents to get their well pump working and why I wish we had the resources to go off grid electrically (very expensive here). I feel fortunate to not only live in a rural area, but to have grown up on a small farm with all the economies and hard work that involves. It hasn't been so many generations since the pioneers that we've forgotten that we can and will survive if need be.