You’re in the middle of a busy week and a colleague asks you if you’re available to help them out with something. You have a tiny bit of space in your schedule and want to be considerate, so you say yes. But the task at hand inevitably ends up taking longer than expected and bleeds into your own working time, leaving you feeling under pressure and more stressed than ever.

Does that sound at all familiar? Whether it’s to lend a hand or get ahead in our own careers, many of us are guilty of biting off more than we can chew at work, and according to Tamu Thomas, author of Women Who Work Too Much, it’s having an unsurprisingly detrimental impact on our health.

How to tell the difference between your capacity and capability at work – and why it matters