I am 60 years old and I started using a fitbit about a year ago.  I find it easy to hit my step goal in the summer but the winter is a different story.  I like the awareness I have now of walking more in the winter.
I prefer swimming and bike riding to walking.  I wish it tracked those exercises as well.  But I find if I put the fitbit in my sock when I ride a bike, it knows I am doing some moderate exercise but it doesn't know what.