[ltadeut]

None.

Just schedule the work you need to do and have some standards for yourself and keep working on it.

If you feel tired after a while you can train yourself to push through it if you really want to. Anyone who's ever run, lifted weights, done martial arts, etc, will tell you your real limit is well beyond your feelings.

If you're still tired, take a break, get a tea or a coffee and just go back to work.

The secret to get work done is to just sit down and do the work. Get used to being bored.