Did you ever have an experience such as going to see a film, or going for a night out, or finally on a date with someone you’d had your eye on for a while, where beforehand you kept thinking “oh my god this is going to be the most amazing, best thing ever”, and then during, or afterwards, you felt “...meh...was ok”.
I’ve set myself up with ridiculous expectations for some things, and then when they haven’t been met I’ve become pretty disappointed, sad, or even depressed. I can create this scenario, or fantasy, in my head, and then I can become trapped in that fantasy, and not actually be present in the moment when it happens. And I think I've not only done this in my life, but sometimes also on the mat: “I’m going to nail this handstand; I’m going to be as flexible as the person next to me, or as flexible/strong as I was yesterday/last class”. I think the idea in yoga is not to live in the fantasy - to drop any expectation. When my reality doesn’t meet or exceed my expectation, then I can become disappointed/unhappy/sad. But if I drop the expectation and can just be in that moment, then I have no choice but to enjoy/appreciate it, as it just...is.
When I step onto the mat I (endeavour to) practice Pratyahara (5th limb of Patañjali's Ashtanga) - withdrawal from the senses. When I let the world fade away I redefine my reality as just me on a tiny rectangle - my mat. I can still have expectations of myself here though, but if/when they’re not met I only have myself to blame. So either I get angry with myself for not being ‘good enough’, or I learn to drop that expectation and just accept the reality - “oh, I fell out of that tree pose - how funny! Never mind, I’ll just try again, or move on to the next pose we’re doing.”. And I think this is why I can feel really good/peaceful/content/happy at the end of a practice - not just because I've moved my body for 60/90/x minutes, but because, through the poses and breath, I've practiced/learned to not live with, or in, expectation, but just to enjoy and appreciate each moment as it unfolds.
However, (and I see this a lot as a teacher,) a lot of the time as soon as people step off the mat they also step out of yoga and are back into their expectations: “oh, yoga - done! Tick. Now must run and catch the train; oh I hope he’s put the children to sleep; I should send that work email tonight rather than tomorrow morning; I wonder how many likes my post has now on Instagram”. And I'm guilty of it myself! I've sometimes completely come out of yoga and returned to the fantasy. But now I'm more aware of it and can endeavour to stop myself.
I think the idea is to take that sense of just ‘being’ with us when we leave the space, as a part of us, and to remain in yoga - connected to the self, dropping those expectations and taking/appreciating/enjoying (hopefully) each moment as it comes.