Your body carries every place your mind wants to visit.

Every place you want to see, every person you want to visit, every thing you intend to do later requires transport, and the transport is your body. Plans made without regard for that assume a vehicle that maintains itself. It does not, and the limits it develops end up quietly editing the list of what you will actually get to do.

Look at what you hope to be doing in fifteen years and ask what physical condition that assumes. Start maintaining that now. The list is only as long as the body can carry.