You're not superhuman
Everyone has a breaking point, but the aim of work isn't to locate it.
Most jobs come with some pressure and stress. Work can sometimes be incredibly stressful, especially when you have tough decisions to make, important meetings to prepare for, or just too much work to do in too little time.
As a good boss, you should protect your team from as many of the stressful things you deal with as possible. Keep them focused on getting their own work done, not worried about or working on everything else that’s on your plate. Give your team the mental headroom to work productively, and only pass on the stress and extra work that they need to deal with.
Put on a brave face or try to carry an unrealistic load for too long, however, and you end up making trouble for yourself and your team. Stress and overwork can be draining and debilitating. They shorten fuses, provoke emotional reactions and undermine relationships. If you carry on for too long, you increase the risk that you’ll explode at your team. Everyone has a breaking point, but the aim of work isn’t to locate it.
Putting on a brave face forever also sets an unrealistic example. Stress and pressure are parts of work. It’s OK to let them affect you: you’re human. If you set out to look like a superhuman, your team may find you intimidating or unapproachable.
Finally, holding back all the pressure denies your team growth opportunities. While we would all love it if work and life were stress free, they aren’t. Exposing your team to some of what you’re facing gives them a chance to develop skills they’ll need to manage pressure and stress later in their careers.