All of Glenn's suggestions are good ones, but none of them address the key factor you (and many of us) are now facing. Our bodies don't recover as quickly and pushing them harder usually ends up working against us rather than helping.

So yeah--try to get into condition. But that sore knee that took five days to heal when you were 28 will now take five weeks or more. So take it easy, smile at the young kids on the trail who are jumping over logs or hopping down steep slopes, and continue to hike in slow, measured steps.

One foot after the other, it's amazing how far you can go....