Office workers, have you found any gadgets that help you keep healthy/active?

[ChooksAndBooks]

DH works in IT. He WFH and has done for years. His work has become more and more demanding and as a result he doesn't get the same time at lunch to get out for a walk. He is basically spending 8-10 hrs a day sitting down and I'm worried about the impact on his health.

With christmas and his birthday coming up soon I was thinking of getting him something that might encourage him to be more active....a Fitbit that buzzes when he's been sitting down for so long maybe....? Can anyone recommend one? It doesn't need to be super fancy.

Any other ideas would be appreciated, although I cant get a standing desk as his study furniture is built in.