I saw a couple postings for sponsorships, which I can not do.
BUT I am interested in a cosponsporhip or dual-check in.
Basically, it works like the regular check in with the added factor that you KNOW your buddy or cosponsor is watching your posts.
ALL they do is give a congrats, yes or ALRIGHT etc. when you hit a goal or task.
If you miss - there is no feed back.
(unless you ask for it - the person can say "ok next time" or "get it tommorrow").
For me it this type of thing is EXTREMELY effective.