There is a website called FutureMe, where you can write an email to be sent to yourself at a date chosen by you in the future.
I've got one in their system awaiting its moment, though I can't now remember what my concerns were at the time of writing or when it will arrive. It's interesting, because it gives you a way to juggle time.
On FutureMe's site, you can read a selection of anonymous emails, and they make poignant reading, like this one:
Did she manage to stop thinking about him? Or perhaps they got back together...Writers are no more bound by chronology than God; we can nip back in the novel's time and change things just like a Time Lord (how handy that would be in real life). So much power confuses me, particularly with the current book, where alternating chapters deal with each heroine. It's hard to ensure one of them doesn't get to Thursday while her alter ego hasn't moved beyond Wednesday morning.