Grammar: “Thought” [duplicate]

Solution 1:

The Handbook of Good English suggests the following:

Direct quotations of thoughts

Thoughts can be treated like other quotations and enclosed in quotation marks. They can also be italicized, without quotation marks. Both of these conventions are common. It is more common to dispense with both quotation marks and italics: Johnson thought, Now why did I say that?; Now why did I say that? he brooded.

You can find plenty of examples of each in books:

• Example with quotes
• Example with italics
• Example with both quotes and italics
• Example with neither quotes nor italics

Whatever you do, the important thing is to be consistent.