It's really important for babies and young children to start going on walks early in their life. Basically, as soon as they can walk they should walk. A Lot. Children gain mass very quickly, and it's essential that their muscles get a chance to develop at the same rate. Babies are born with the ability to hold themselves up, but if we start them off right away with passive positioning (car seat, bouncy chair, cradled in your arm) then they gain mass but do not get any muscle development along with it. That means that the muscle they have is no longer strong enough to hold them up. It's the same for their legs. They should go for a walk every single day, for as long as it takes for them to reach their limit. Some days it's gonna be 10 minutes around the block, some days it might be 45 minutes before they need a break. Don't shy away from difficult terrain either. Just let them do it. That way they're building their endurance and strength, their muscles will never be too weak to support them.
Don't forget that their little feet are always growing and developing too, so be sure to keep them out of stiff, bulky shoes and in non-restrictive thin soled footwear. That will give the foot muscles a chance to develop properly as well. And never EVER let your kid wear shoes that are too small.
Getting our kids out walking does amazing things for all of you! It's so great for your body, but it also creates some wonderful memories. I know it's one of the things I remember most about my childhood. Walking with my mom on a rock beach on a sunny summer afternoon, padding along after the first snowfall in the dark singing Christmas carols, scooting over to the park after work with mom and dad to take a walk in the back trails. It's something we still do to this day when we're in the same city, and I'm almost 30 years old now. That's more than 25 years of creating something special with my folks. And check me out now, repeating the cycle with my own chicklet!
Start young. Don't mind the weather. Dont' mind the time. Find exciting places. Walk the same boring route. Go with friends. Go for hours. Go for 10 minutes. Go as often as your kid asks. No one's ever said "well that walk was a waste of time" (unless they're stupid). No one's ever said "I wish I spent less time walking with Mom and Dad and more time watching tv alone in my room." No one's ever said "We should have spent more time in the car."
Thanks a lot to my dad who spent this walk with a camera stuck to his face. I really appreciate it. :)