Sometimes age does catch up and even with all the cardio it is still difficult to maintain physical condition over a 5-7 day hunt. You just don't have the reserve you once had younger. But if you have the will to do it, do what you can while you still can. It might not be what a 45 year old can do but if you are in the mountains and walking what does it matter. Smell the air, take in the sights, laugh with your friends and guides/outfitter if you use one. I will be 70 shortly and still plan on going this fall but I know every year it gets more difficult to train let alone get your gear together. But I think of hearing a lone bugle once more and it gets me another mile or two in the walk. So my message is keep going if you have the will to do so and enjoy whatever the hunt may be. If you can go a mile, go, if you can go 5 miles, go, doesn't matter, you are still hunting and that is all that matters.