Great news -- Jennifer Lopez and Alex Rodriguez woke up with even more chiseled bodies! Now back to your doughnut.

The couple got in a yoga workout Friday in NYC, and based on this glimpse of their abs ... it was a good one. Not that it shows -- even a little -- but this was the day after Alex celebrated his 42nd birthday ... and a few days after J Lo's 48th!

As the saying goes: couples that sweat together ... make other couples super envious.