feel

I was sad. Now I feel different. I am happy.

langtraveler Are both of them correct?

No. Only the adjective is appropriate with the linking verb 'feel'.

Thank you for reply.
But how is it differ from this sentence which says"he felt differently?"

"I asked Matthew whether he was still feeling the same way about the problem as he had at first. He said he felt differently and that from now on he would help the new kid." (Positive Discipline : A Teacher's A-Z Guide, Jane Nelsen, Ed.D.,Linda Escobar)

In your latter example, 'feel' means 'think'.

Thank you very much for your reply!
Could I ask one more?
As a learner, I'm curious how do you discern 'feel that means think' from just 'feel.'
I thought that the original sentence meant "he said that he wasn't angry anymore" and in that case, isn't it incorrect to say "felt differently?"

It's a matter of whether you feel 'something' (as an object) or you 'have a feeling' (intransitive).

Always thank you very much for your reply.