I'm just being a teenager

Would look more convincing with proper grammar...

Teenagers do stupid things so maybe its both.

Welllll, not laziness, tiredness I get but being lazy isn't being a "teenager"

Except laziness itself is bad behavior.

but what if I'm not a teenager but I"m still lazy

http://www.telegraph.co.uk/news/science/science-news/11410483/Revealed-the-science-behind-teenage-laziness.html