What is laziness?

Let’s try to be specific. Consider these cases:

a) a person having difficulty getting out of bed. hitting the snooze button over and over..

b) a person who doesn’t get around to studying. procrastinates instead.

c) a person who doesn’t get around to starting an exercise plan.

d) a person who one day puts off doing the dishes.

How should laziness be defined?

dictionary.com says:
“averse or disinclined to work, activity, or exertion; indolent.”

But what I’m trying to figure out is what causes the aversion? Most tasks are tasks that an individual believes is best to do, so why would they be averse to it?