I always want to know the difference between could and would.
1) I think I could do it.
2) I think I would do it.
Please tell me which is correct.I also want to know the difference between these two.
1: I think I would be able to do it.
2: I think I would be willing to do it.
Very often, though, the two sentences mean almost the same. But "could" focuses on ability (it could be ability to overcome your natural distaste or to ignore some taboo), while "would" focuses on willingness.