In our office we started a lunchtime walk. We eat our lunch and whoever wants to participate, we head out for a 30 minute walk. It might not be enough, but it's better than the nothing before.
It will likely require a shower afterwards though which might pose a problem.
1) A 60 degree F room to stave off sweating
2) Enough exercise to be healthy but that stops just short of making you sweat
3) (2) is variable based on body weight of course
Sometimes the practical solution isn't the most efficient.
I mean if you're chatting with coworkers and relaxing during the walk then it's a different story - but if you're just in to it for health benefits - like I've seen people suggest walking home from work, etc. - just take the shorter route and do proper exercise.
Threre are a couple health benefits that walking has over HIIT. For my particular case, my doctor told me that the amount of time I sustained an elevated heart rate was more important than how hard I pushed myself (don't try to walk the same distance in a shorter time, instead walk for longer). And there are cognitive benefits unique to walking [1].
I can't speak for anyone else, but waking turned out to be my gateway drug to all kinds of other healthy lifestyle changes.
[1] https://www.theatlantic.com/health/archive/2014/10/walking-f...