Want to respond to letters - complete the report - read a book - spend quality time with family?
Try turning off the router for an hour. Handling impulsiveness is easy, you just have to:
Throw away the key: Close off tempting alternatives.
Setup a couple of Pomodoros to complete the job; or talk the matters with your complete presence. Don’t let your impulsiveness distract you! Your job will end up better and your clients will be happier.
Similar “tempting alternatives” might include: phone, television, tickers, IMs etc. When work starts expanding, turn these off - focus, and you can happily return to them after that.