Yes busy or having no time are common excuses to not exercise besides being lazy. Or the gym is too expensive, far from the home or office. In my last workplace I discovered a few things that the company did and I myself did (out of stress) that unknowingly made me "exercise". I moved more than I used to and managed to trick myself to be more healthy.
1. Instead of emailing a co-worker who is sitting in the same office as me, I walk over and talk to him/her instead. The office was huge and I can clock 100 steps just by walking back and forth. Moreover it's more personal than a cold email that nobody needs more of.
2. Delete all the food delivery apps or keep eating at the same place around the block. Walk to a new restaurant or cafe for lunch and discover new places so you won't be bored of the lunch options!
3. Start a steps challenge amongst colleagues, make it competitive by offering attractive rewards for the people with the most steps. In my previous job the entire company got really competitive and some people clocked crazy steps like 30,000 everyday for a period of time.
4. Invest in a good nice big water bottle for your desk which you will keep drinking water from. This makes you stay hydrated in an air conditioned room and also makes you keep walking back and forth to the washroom to pee! I have TWO water bottles filled all the time and they are the real game changers in my office routine.
5. This is a no brainer but climb stairs. If you hate to climb up, try perhaps three storeys at first and increase as you get fitter and feel better.