Do not lose height when walking in the hills or mountains.
My late uncle spent a considerable amount of time in the mountains of Yugoslavia during WWII.
Once during the 1950s he and I were walking up large granite hill in the Matopo Hills near Bulawayo in the then Southern Rhodesia.
His advice: When you climb a hill, if possible, take a line that does not go down and then up. This way you will not lose the height you have gained and save energy.