The Shayar is saying how happy he was while he was alive.

This powerful couplet, from Mir Taqi Mir, speaks to the complexity of love and illusion. The poet suggests that the joy (khush rehna) one experiences while living is only temporary, a mere phase. He implies that the true reality—the 'Qalandar' spirit, the unrestrained self—is something that is always known, always present, regardless of the transient happiness. It's a reminder to embrace the raw truth rather than the fleeting comfort.