:salam2:
When we develop an intimacy with a fellow human, then we tend to easily think aloud. The thought and dialogue happens within our mind usually. But when we develop an intimacy or closeness with another person, somewhere within out consience, we start feeling the person we are close to is a part of us. And that is when, words flow unrestrained. Words of affection flows unrestained, words of hate too if unchekced will flow unrestrained.
In your fathers case, you assess him to be less optimistic than you are. That usually happens with age, experiences sometimes has a way to dampen and slowdown. The youth always wants to do, jump to action
So take those doubts positively. They are just thoughts. Take them as inputs for you to examine. Be confident, see if there is merit in those thoughts, use the valid points and strengthen your plans and actions. Do not look back at the thoughts that are negative and not valid. Be confident, avoid the trap, learn from mistakes.
Keep repeating - 'positive thought is progress'. Become wise and Turn your dad young in mind!
May Almighty Allah the wise, The bestower , bestow us with the right thoughts and action to succeed in here and hereafter... Ameen!