i keep dumbbells near my desk as an effort to fight off my increasing softness. these are simple to do during work.

Will the motions do you good even without the dumbbells?

Or is the added weight the point?

The motions without weight will be good for you too. Air squats are a good workout.

added weight only advances your muscle building

Body weight squats (air squats as you call them) are great and tiring.

I keep a pair of 10-pound dumbbells for this workout:

If it's good enough for the NFL, it's good enough for me.