You don't need confidence to do activity; you just need sense. Function according to your capabilities, neither confident nor diffident. Only an ego can feel diffident or confident. What is it you call as 'ego'? Is there a distinction between what you call as 'myself' and what you call as 'my ego'? They are mixed up somewhere; either you have become your ego, or your ego has become you, whichever way. What you are referring to as ego is not something you got because you did something well, not because you became rich, beautiful, or developed muscles. When you started kicking in your mother's womb, the ego was born. The very first time you got identified with your physical body, the ego was born.
The ego is a defence mechanism. You got identified with this little body. You have to survive in vast existence of which you have no perception to even know where it begins and where it ends. Just to survive, you have to project yourself as 'big', so the ego is born. It is false reality. What you are referring to as confidence is false identity you created for the sake of survival.
The ego is like your shadow. The moment you have a physical body, you have a shadow. The shadow itself is neither good nor bad. If the sun is up there, you have a little shadow; if the sun is down there, you have a mile-long shadow. So your shadow depends on the situation outside. So, too, your ego.
You need different kinds of identities to deal with different situations. If you are fluid about it, if you can change from one to another gracefully, then you can play your role to the hilt and still have no problem with it. The problem is you get so identified with it, you start believing you are that. Once you believe 'I am the shadow', what would you do? You would naturally crawl upon the earth. Then, how will life be? If the floor is carpeted, you will crawl in comfort, not in joy. Suppose there are stones, rocks and thorns? Then you will cry. That is how your life is going on right now.
Why i am saying you are crawling upon the earth is because right now your whole experience of life is limited to the physical. Everything that you know through your five sense perceptions is physical, and the physical has no purpose of its own, it is there only as a peel to the fruit. Only as a protective layer to the fruit the peel means something. The body is important because there is something else inside that you have never experienced. If that something else goes away tomorrow morning, nobody wants to touch this body. So today when it is there, we have to take care of it, it is everything.
If we do not transcend the limitations of the physical, life will be a struggle, swinging between confidence and diffidence. If situations go well, you are confident, if not, you are diffident. And you know, any moment, life can just change course.
If everything in the world is going terribly wrong for you, and you can still go through this life untouched, peacefully, joyfully within yourself, then you know life the way it is.
Otherwise you are just a slave of the physical.