I say play, because really that is what it is. It's work, yes - there is a level of physical preparation and opening that needs to happen, and that can be quite arduous. Should be, that's one of the benefits of the asana practice; good, solid, body-toning and opening work. But, from that foundation of work, maybe we can then engage the play.
When we were kids, and some of us did that long enough ago that Leggos were space-aged, and TV had 2 or 3 channels, and a knob to turn to switch 'em - but I digress. When we were kids, we played outside all the time, and we did things just to see if we could do them. And, lived to tell the tale. Sure, we even did stupid stuff...
But, it was that spirit, not of childishness, but of playfulness, and 'why not' vs 'what if'. It's the ability to put energy and effort into it without taking it too seriously, and knowing at the end of the day, it's good and you had a good time, and maybe amazed yourself; or maybe fell on your face, with a smile on it. Failure, of the safest, sweetest kind.
I like arm-balancing and teaching them, no secret. I like it because it's like that - it's playful, but disciplined; it's freeing, but relies on solid foundation, it allows for expression and lightness and a feeling of playing in the edges of the laws of physics, at it's best. At it's worst, you do some face-planting, you get some interesting bruises, you find incredible twisted-shaped ways to fall and we learn - it's good, it's fun, if we catch flight, it's a perspective shifter. It makes things different.
Bring discipline to the practice, for sure. And be solemn when it's appropriate, but be light and joyful. Remember play is action, taken in joy, not 'pass or fail'. You can take some risks, on the mat. You can show yourself that there's a difference between failing and being a failure - that failure is not fatal. And you can grow, learn, apply and perhaps fly!
It's not the perfect conclusion, but as I play on about playing on, playaz, I want to offer a closing quote. I got spiraled into a science blog earlier, and I came across this; I don't think in the context it was originally posted that they took him to say 'playing' was a positive, but it did get me thinking.
Just a little before his death, Isaac Newton (1642-1727) is supposed to have remarked:
'I don't know what I may seem to the world, but as to myself, I seem to have been only like a boy playing on the sea-shore and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me.'
Stand at the edge of that great ocean of truth - it'll take care of itself. You; go play, and give thanks and praise.