I've worked remotely for 20 years on both salary and hourly (consulting). I found it especially hard to 'unplug' when working hourly, as you always feel like you could be making money. Doing laundry? You can get an hour billable while waiting. Watching a movie? Is the movie good enough you want to give up 2 hours billable? Also, this can be a lot worse when you're younger, just starting out, and money is generally tighter...Kids, mortgage, school loans can all make extra money from overtime very attractive.

On salary, I find its easy to lose track of time on an interesting problem. You get 'in the zone' and time just flies by...

As I've gotten older the first problem has sort of naturally resolved itself, as I start to value leisure over bill rate. Getting older - not only does your income tend to go up, but expenses can come down. Things like school loans, car notes and mortgages may be paid off. Kids grow up and become established in their own careers, requiring less support.

I still have the second problem though. In this case, I generally find having other _people_ ping me to be much more effective then alarms and to-do lists. Its too easy to turn off an alarm or ignore a list. Interacting with an actual person is much harder to ignore :-P