I don't think much of Jack; he is so absent-minded.
- Out of sight, out of mind.
- give (someone) a piece of one's mind
- all in (someone's) mind
- have a lot on one's mind
- have half a mind to do (something)
- keep (someone or something) in mind
- bear (someone or something) in mind
- on one's mind
- mind is buzzing
- take one's mind off (something)
- have a mind of its own
- change (someone's) mind
- last thing on (someone's) mind
- boggle one's mind
- meeting of minds