As others have said, walking some and possibly doing some backpacking will help. The better shape you are in at the start the easier it will be. You see a lot of people get discouraged early on because they can’t do the miles like some others and ‘fall behind.’ It isn’t a race so why does that matter? But it is hard when you meet people you enjoy hiking around but they pull way out ahead of you and then you never see them again.
If you do nothing you will be fine as long as you realize you need to go slow and not push yourself too hard. You will probably injure yourself if you do…or burnout early. You have to get plenty of rest as your body adjust itself to the demands you place on it. After a month, most hikers will all be good physical condition and the avg daily miles will be similar, with some exceptions for the super fast/slow hikers.
Having said that I remember hiking with a hiker named Dan who was in his 60s and I was constantly amazed at how fast he could go down hills WITHOUT hiking poles. Downhills are the worse thing for your knees it seems. At least it was for me. Saw a lot of people leave the trail with knee injuries. You see a LOT of people wearing knee braces after a couple weeks. I only made it 580 miles and knees still aren’t the same. I cannot run now the pain is so bad and fear I may have done permanent damage. And I love to run BTW. I asked Dan how he could do the downhills so fast and he told me he had spent a couple years getting ready for a thru hike and did a lot of strenght training on his legs.
Wouldn’t hurt to go to the gym and build up some muscle in your legs. I know from running, the more muscle you add with strenght training, the fewer injuries I had and your body can store more glycogen (carbs) in your increased muscle mass. Marathon training is all about teaching your body to store more glycogen, and burn it more efficiently, so you will be able to get to the 20 mile mark. It is the last 6 miles when you are out of stored energy the “fun” begins. The point is, you will be able to do longer miles early in the hike if you have more energy at the end of the day. Could be important for those who have time constraints and need to finish a hike in 4 months vice 6 for example.
Rerun