Some things I've tried:
Cold Showers - I rented a period property last winter and the boiler wasn't very efficient, so to save money I took cold showers instead of heated. These make you feel amazing and I can definitely vouch for them.
No Internet - I once had a real problem with wasting time online (Youtube, forums, whatever), so one day I experimented with cutting off my internet access. I haven't looked back to be honest! I'm way more productive now, and whenever I need to access the internet I just bring my laptop to a cafe with WiFi. Grabbing a coffee might not be very Mustachian, but hey I'm not paying for home internet. :) My phone has 1Gb of data which is all I need for using Maps, WhatsApp and random other things. Most towns are littered with WiFi hot spots anyway.
No Car - I've never owned a car. Bikes take me most places, and for longer journeys I take the train. While a train journey is typically slower than a car journey (inc. waiting times and traveling to the station itself), I'm also free to do things I couldn't do while driving (read a book, meditate, stretch my legs, etc), so the time is of higher quality.