I tend to let my eyes do more of the traveling rather than my legs. When I was young (and fairly dumb) I used to cover as many miles in a day as possible. I often came upon running game tracks...I wonder why? Once I slowed down I started seeing more game rather than just their tracks!
Trekking poles are great on uneven terrain...especially when carrying a hefty pack. They not only stabilize but put a lot less stress on knees, thighs, and back. I don't hunt too much using poles (they are pretty darn noisy) but they are great for hauling camp/meat.
As LopeHunter mentioned above, I've also improved my gear. Replacing heavy, bulky items with smaller-lighter weight gear certainly helps. Obviously this comes at a pretty high $ price!
Lastly, I have a job working outdoors where I stay in super shape year round. I really think having a healthy diet and staying active year round will pay big dividends as I get older. I do an incredible amount of hiking on steep, uneven terrain that is similar to what I do every day hunting.