What is a word for somebody who lies to themselves

I feel like the fact that people lie to themselves about things can tell you a lot about that person but I just can't put my finger on a single word that I'd use to describe them. In fact, not just describe them, but truly convey that they lie to themselves.

Example of a person who lies to themself: "I will do all my work tomorrow, I swear."

Solution 1:

Self-deluding.

A delusion is a belief or idea that is not true. To delude yourself is to convince yourself to believe an idea that is not true.

Solution 2:

Such a person is said to engage in self-deception.

Solution 3:

The truly single word for this is perhaps delusional.

Or am I deluding myself?

Solution 4:

They are simply fooling themselves.