I read constantly in my teens and 20s. My reading declined in my 30s due largely to my workload and schedule. It bottomed out in my 40s and 50s when I was a stay-at-home dad, and very busy with kids, homework, after school activities, etc.
But my son left for college last year and my reading picked up a bit; my daughter left for college a couple of months ago and my reading really picked up. Now that I've made the transition from stay-at-home dad to merely unemployed I finally have time to read all those books I put off -- and then some!
Maybe, if your reading has declined as you've aged, you just haven't lived long enough yet.