3 Ways to Do Good (and Feel Good) on Your Next Vacation

...Nature Trails

Pack Your Bag: Every year Sierra Club volunteers donate 25,000 hours to help preserve hiking trails for future travelers. Projects range from rooting out invasive plants in California's Yosemite Valley to rebuilding trails in Kentucky's Mammoth Cave. Family programs mean preservationists as young as 5 can get their hands dirty for a greater cause.

Time Commitment: typically one week

Cost: $315 to $1,975, including meals and lodging

Quick Trip: The Appalachian Mountain Club and the Tahoe Rim Trail Association offer weekend trail repair projects.