Early in my career I was accused of being overconfident and even cocky, but I really was confident that I had done the training and didn't see any other reason to say otherwise.
Whatever we accomplish in life, if it's solely for our own good, then it doesn't mean that much. The things you do that affect others in a positive way are the ones that count. Whatever facet of life you're in, God has given you a gift; do the best you can with that gift.