I walk DD to and from school every single day, rain or shine. Sometimes, I walk extra after dropping her off or before picking her up. We walk to the library and certain places in our community. When running errands, I choose the location with care so that I can park once and walk between the places. Saves money on gas and frustration with parking and adds exercise and sunshine time (vitamin D making and better eye health -- remove glasses whenever possible).
As a family, we hike and swim (ocean and pool) and walk and ride bikes. All for free.
I also take free exercise classes through our city's adult continuing ed program. Technically, most of the free classes are intended for older adults (55+), but as long as a certain percent of the students fall into that category anyone else can attend as well. I am usually the only student under 55 (or a friend of mine and me) and the instructors never mind.
When our playgroup first started, we were a baby hiking group. We met twice a week during the week (moms and babies, although we have some dads who joined us on their days off when it worked out) and twice a month on weekends for family hikes. We'd put the babies in packs or jogging strollers and go. When they started fussing about being carried, we slowed down A LOT but still hiked with them toddling along on foot on easy trails. We still go camping once a year as a group and go hiking in Yosemite and Idylwild and other such places. Two of the kids hiked Vernal Falls in Yosemite at age 4! Those two kids (mine is one of them) still have amazing stamina for walking, running, and hiking on a regular basis. Us moms still get together a few times a year to hike nearby. (We also get together for social reasons, like our annual New Year's Eve party -- which is early and kid-friendly.)
I meet up with a different friend once a month to walk along the beach for hours.
Some friends and I took cheap belly dancing classes one time and then met at my house to practice with a DVD my aunt gave me. That was so much FUN!!!