easy 40 minute run and moved 600 pound piano

Today I had to move my piano a few feet. My piano is a yamaha s6 grand and is has factory castor wheels on carpet. I was able to lift it enough to move it. It was extremely heavy. Probably had lifted about 300-400 lbs to get it to move. It took three people in the past. I thought it would be fun challenge to do it solo. I also went out for a nice 6 mile run in the sleet.