If you usually work from home - get away from the office for a day.
Escape from the phone and the internet and go and find an office away from the office. Mine is the Seattle Hotel down at the Brighton Marina. It's usually relatively quiet, plenty of space, comfy chairs, tables to sit at if you want, places to plug in a laptop and decent (if somewhat over priced) coffee. The staff are relaxed, casually dressed, leave you in peace but attentive in a quiet, unassuming way. There's a pleasant informality about the Seattle - stuffy business suits seem out of place.
It's a great place to have some quiet time, away from distractions, to get on with your work. I'd arranged a 1:1 meeting there at lunchtime and had the local Brighton Chamber meeting in the evening, so it was an ideal opportunity to spend a few hours putting together some ideas I'd been thinking about for a while.
These days there are plenty of places where you can get a coffee, tea (or your drink of choice), sit with your laptop, a book, notes or writing materials and have a couple of really productive hours.