Lawn Mowing 101

So I guess I was left out of the loop when someone, somewhere had a lawn mowing 101 course. As I was being the faithful wife that I am today and was mowing the lawn. I see my neighbor walking over to me. At this exact moment I was pushing the mower uphill trying to get under a tree/bush in my front yard. He said "you know, it is much more efficient to start uphill and go back and forth" He made some hand gestures and I pretended to understand and said "Well, I like the work out" he said "that's too much of a work out". SO, I kept on mowing and this time I went back and forth like I thought his hand gesture meant and then as I am just about finished with the lawn it dawns on me what he meant. As I am at the top of the hill mowing because I had started at the bottom and worked my way up. After he plainly told me to start at the top and work down. I guess I just didn't get the concept until it was too late. Anyway, I thought I had better go over and talk to him and make a joke because he obviously continued to watch me mow it all wrong. I explained to him what an idiot I was and he replies "Thats the first thing they teach us in mowing 101" ummm.... I must have missed that memo