Physics on a hill

This Sunday, justin was riding erin's bike around her neighborhood exploring the different streets of kapahulu.  He had already gone down the other end of the street, but was reluctant to climb the mountain at the other end a little afraid he couldn't handle it without walking the bike up the hill.  He remembered he was a man and could do anything so he contemplated whether it would be easier to go straight up or to gradually zig-zag up the hill.  Because of physics class, i already knew the answer, but said nothing when justin said he would find out which technique would require less work.  As a result, he experimented and went up twice both ways.  The first time he went up the hill somewhat quickly, but looked quite winded at the top and took him a while to come back down as he caught his breath.  As he neared the top of the hill, he could feel the potential energy building as it got harder and harder to peddle.  When he rolled down the hill i noticed his kinetic energy was building and potential energy was decreasing.  The second time he zig-zagged up and it seemed to be a lot easier and less strenuous, although it took him forever to get up.  He realized, if he used more energy to get up the hill, he took less time, but when he put in less energy, he took longer to get up the hill.   So justin learned today that either way he went up the hill he put in the same amount of work.