I dug one little ditch today

OK I dug one little ditch today. Repairing a broken water line and my shoulders and back are killing me. I have done this kind of stuff before. So whats up with all the pain now?. After some thought on this troubling matter, I have come up with a few possibilities .
1. Dirt is heaver now than back in the day.
2. Because of Global warming the gravitational pull under my house is stronger now. Making me work harder.
3. God is punishing me for wasting water.
4. Fucking Obama.
5. I'm just an out of shape old fart.
I'm going with number 1.