What to focus ?

When I am giving speech, I should not focus on people or what are they thinking about me? But .. simply focus on the “subject”, that you want to convey.

when I am wearing glasses first time, I should not focus on how I look or what others are thinking about me? Just focus on the sight and eye comfort. Think about glasses when you are buying those and testing those.

give 2 more examples about what to focus on what time ?