This is obvious in theory but hard in practice.
The people working for you are not (yet) as good as you are at everything. A new task arrives. You could delegate it to one of your minions, but that would take an hour of explanation and they’d probably do it wrong anyway so you’d have to re-do it. The task is quite urgent, so even though you are busy you just do it yourself. Sound familiar?
Where at all possible, force yourself to delegate the task, even if it takes much longer. Keep remembering the long-term benefits of training people up, even if it makes the fire currently burning on your desk a bit worse temporarily. Hopefully you have hired quick learners, so you’ll start to see the payback soon!