Did four tai chi forms this morning, 10 push-ups, twenty squats. My arm is still sore from whatever I did to it that makes push-ups so unappealing. But at least I’ve started being able to do push-ups again.
I’m finding that four tai chi forms is about the right number for me right now. Each iteration of the form, with a slightly different emphasis each time, is causing me to break out into a light sweat, and feel the presence of chi — that is, the sense of tingling that to me represents the widening or growth-in-effectiveness of the channels of chi-movement in the body, the meridians.  
I don’t know that this is true… but it feels like when you’re a few weeks into tai chi practice, you get a sense of energy or tingling or cold or heat in the extremities, a sense of power. Sometimes, after a few months of practice, you can project this power. And then at some point, this power just sort of dissipates. Goes away.
Except that it doesn’t. It’s just that you can’t feel it. The energy channels have deepened and gotten wider, and the flow is much larger and stronger. But you’ve internalized it to a much greater degree, and it’s no longer a unique sensation. So you have to work harder, or at least more frequently, and in greater depth of practice, in order to experience that same awareness.  
And I think this is what has happened with me. And I think that I’ve hit the point in my own practice where four repetitions of the form, a little qi gong and some push-ups and squats activate these channels just to the point where their ability to move energy is challenged. And then I can feel the flow of chi quite easily.  
Alternatively, I can try talking my way through the tai chi form once to my students on Mondays, and be utterly drenched in sweat. The talking while doing is both empowering and exhausting.