I don't think much of Jack; he is so absent-minded.
- keep (someone or something) in mind
- give (someone) a piece of one's mind
- Out of sight, out of mind.
- weigh on (someone's) mind
- have a mind of its own
- have a one-track mind
- have an open mind about (something)
- have the presence of mind to (do something)
- get a load off one's mind
- last thing on (someone's) mind
- cross (someone's) mind
- have a lot on one's mind
- boggle one's mind
- take one's mind off (something)