They're all correct but they carry different meanings. "I did what I thought was right" = You did whatever you thought was right at the time, in your opinion. "I did what was thought to be right" = This is UNUSUAL. It's not incorrect though... You would use it to say that you DID what was THOUGHT TO BE RIGHT by MOST PEOPLE/CONVENTIONALLY at the time when you did it. "I think it's what I thought it was" = You STILL think that something is the same as you PREVIOUSLY thought it was. "I think it's what it was thought to be" = UNUSUAL. It carries the meaning that you CURRENTLY think that something is the same as it was PREVIOUSLY thought of by MOST PEOPLE/CONVENTIONALLY. --- I hope this helps :)! Good luck and take care -.-! PS. On an unrelated note but it's something I've seen you do often. Your initial question should be: "How would you say it? Naturally?" The reason is because natural is being used as an ADVERB (naturally) and is relating to the verb "say". Just letting you know!