My son has 3 problems that are attributed to lazy:
1 - fine and gross motor skills (even though he has the hyperactivity with-ADHD, he also has fine and gross motor skill problems. Writing, walking, running, etc., tires him after a while. It just takes more energy for him than the regular kid. (It appears to be laziness.)
2 - organizing things so he can tackle a job like cleaning his room, homework, etc., is overwhelming so he avoids or shuts down. (It appears to be laziness.)
3- then there are the times it is just pure laziness and/or he just doesn't want to do a task like picking up limbs from the yard. When he was little, he use to say he was allergic to work. lol Some things never change, I guess. When he has to take a break from doing "x" after 5 minutes because he is sooooo tired, but takes that break jumping on the trampoline I put it in the "don't want to"/lazy category. lol