optimist

Example:He's a pessimist and always expects the worst.

Definition:A person who tends to expect the worst possible outcome and view the world in a negative light; a pessimist is someone who maintains a negative attitude in the face of difficulties and challenges, believing that bad things will happen or continue to happen.

Example:A realist would approach the problem with a clear and practical mindset.

Definition:A person who is realistic and takes an objective, practical, and rational approach to life, acknowledging the problems and difficulties but not necessarily avoiding them.

Example:The skeptical scientist asked for more evidence before accepting the new theory.

Definition:Doubtful, distrustful, or suspicious of something, not easily convinced of its truth or validity; a skeptical person is one who questions or doubts the validity of claims or statements.