See our blog "Revitalize your office: how active microbreaks can boost desk workers’ wellbeing and performance" for more information on the science.
This sequence includes 10 ideas for microbreaks including light exercise that will fit the bill. Try those that appeal, and see what others you can come up with that suit your own circumstances. If you are sitting or static for much of your working day, every minute that you move really does make a difference.