Re: "I'm too tired"
My kids had that phase. When they said that they were tired, they were made to take a nap for at least 5 minutes. Once in a while they'd fall asleep, probably from boredom, but most of the time they'd come back out and be 'refreshed'. I try to keep natural consequence, to being tired means you nap and being bored means you get assigned chores/something to do.
Wife to H & Homeschool Mom to
The Nerd (11), The Scientist (8) & The Entertainer (5)