Buy and use a standing desk. 1 hour of gym will not fix sitting 8 hours a days. I did that as an experiment in covid home office time and after a few months it fixed all my back and neck problems.

For many more details I can recommend

Starret(2016): Deskbound: Standing Up to a Sitting World

https://www.amazon.com/Deskbound-Standing-Up-Sitting-World/d...