I work about 5-6 hours outside of my company's primary time zone, but they tend to try and keep any meetings I need to attend to after 6am or so in my time zone. I don't have much trouble being motivated to work, I am only part time for now anyways, but I do get out and do a daily walk before I do anything heavy for the day, so I'll do some meetings, planning, and admin in the mornings then walk then I have energy to sling code for 4-6 hours.
Some days I just don't work, and I learned to give myself the day (rarely two) but get back to work with a strong day the following day to regain my momentum. I find momentum is key in working remotely, you have to maintain a steady pace and not go too hard or too easy or else you're going to burn out or develop bad habits.
I tend to work whatever days are necessary, weekend or whatever. My life is very flexible, so sometimes I'll have a mid-week weekend and work the weekend instead.
tl;dr: momentum is key, try and work at least a few hours a day and ensure you maintain a steady pace over time without doing death-marches or being lazy.