Great question — answering as the UphillTech team:
Gym training, especially body building, weight training, and strength training do not translate well to hiking, so don't count on that to carry you and get you through. If you are new to hiking/backpacking, I would advise the following for "first hikes": Not more than five miles Not more than one night Test hike with your planned shoe/sock combo Eat like you would to work out Written checklist for gear Specifically as a weight trainer, watch out for these mistakes: Don't carry too much. Most weight trainers who go with us overload the first time. It kills their feet. Yes, you can easily lift a 50lb pack. Your feet cannot yet handle that for mile after mile. Get good shoes. Gym clothes are...
Full answer by Russell Steen: https://outdoors.stackexchange.com/a/3721 (CC BY-SA 3.0).
Need it done for your business? UphillTech.