I can't tell you why Michael is crying here. I am the one who just finished working out, so if anyone should be crying it is me. But notice he is doing his new favorite thing: standing.
And here you can see he is standing again, but happy this time. The moral of this story is that my life is about to change drastically. Once he starts walking, I am in serious trouble. And by the look on his face here, he knows it.