One of the best things my old Dad taught me was not to take myself too seriously; as this little poem says:
Sometime, when you’re feeling important,
Sometime, when your ego’s in bloom.
Sometime, when you take it for granted
You’re the best qualified in the room.
Sometime, when you feel that your going
Would leave an unfillable hole.
Just follow this simple instruction,
And see how it humbles your soul.

Take a bucket and fill it with water,
Put your hand in it, up to the wrist;
Pull it out; and the hole that’s remaining
Is a measure of how you’ll be missed.
You may splash all you wish when you enter,
You can stir up the water galore.
But stop; and you’ll find in a minute
That it looks quite the same as before.

The moral is: Be proud of yourself, but remember, there’s more to life than being indispensable.