If you can jet up to the side of the floating island, then you can climb the vertical wall without using any of your jet pack fuel as long as you keep pressed forward against the wall. You keep using the jet button, but it doesn't use any jet pack fuel this way.
There is this other thing you can do with the jet pack, and that is run, melee, and jump with the jet pack. That will move you forward faster than running. You have to immediately jump after pressing melee. If you do this maneuver all the time, then you don't need a lot of stamina to run. There is a similar maneuver near the end of the game Half Life when you get this suit that lets you jump long distances fast.
There is this other thing you can do with the jet pack, and that is run, melee, and jump with the jet pack. That will move you forward faster than running. You have to immediately jump after pressing melee. If you do this maneuver all the time, then you don't need a lot of stamina to run. There is a similar maneuver near the end of the game Half Life when you get this suit that lets you jump long distances fast.