To start a world tour you have to be physically and mentally fit.
It's one thing to do a day trip every sunday during the motorcycling season and ride sometimes after work. It's another thing to drive around the world on a fully loaded motorcycle and travel almost every day. A good strength and endurance training helps to master the journey.
The first step of the training can be a walk, every day a small walk of 30-60 minutes, in any weather, helps the body to strengthen its immunity. The second step is a healthy diet. A varied diet strengthens body and mind and prepares you to eat unfamiliar food. Because not in every country you can find the products that you know since childhood. Another step is to visit a gym. Here you can get a targeted and supervised muscle and endurance training and exercise regularly.
The biggest enemy of fitness training is mostly the inner bastard. Walking alone or visiting the fitness center demotivates many. Nevertheless, you have to overcome yourself and do it. And who knows maybe you can persuade one or the other friend to do the training together or find new friends.