One's schedule inevitably turns into whatever they let it. If you're one that's naturally going to want to join every call or be around for the most active chat periods then no amount of caffeine or motivation is going to make the schedule you decide to keep sane. I'd heavily recommend staying away from caffeine to try to solve tiredness, at best it temporarily masks any symptoms while the problem remains at the end of the day.
Motivation itself isn't that much different than other remote jobs. Make sure it's something you're interested in working on, try to make a few close work buddies, and go enjoy life when the time you said you were going to clock out comes.