Since I am right handed, when I climb I tend to reach up with my right hand/arm and pull with that, while my left follows. It was kind of a slap in the head, duh, kind of moment when he said that. So last night I consciously tried leading with my left arm, and it was difficult! So, that's my training for climbing now. I need to get balanced. I can belay both left and right handed. Now I have to climb both left and right handed. It will balance out my back.
I included two women climbing photos to have photos on the post, but it's kind of a lesson for the day also. Photo 1 is trad/crack climbing. Photo 2 is sport climbing. Both photos have a major thing wrong with them - NO HELMET! Stupid women. Photo 2 shows why so many men want to photograph women climbers - you get a good view of the rack. And I don't mean the climbing gear.