Exercise whilst sitting at a desk

Thomas_Holding

I spend a lot of time at a desk at home - any ideas on how I can exercise doing this?
Ideally without buying something that needs assembling.
Thank you in advance for your help.

MrsStepford

Husband has been working from home since March 2020 most of the time. I bought him this
Pedal Exerciser - Blue - UNIVERSAL - M057X - Damart

You could google exercises for older people and try those using a chair. 

Spoonie_Turtle

Pedals are good, resistance bands, a gym ball to sit on instead of a chair.  Instead of pedals you could maybe use tins to roll your feet back and forth but I'm not sure that engages as many muscles.

YouTube probably has lots of chair exercises; ones without resistance (leg raises, ankle circles etc.) are least likely to need equipment.