There's a difference between being lazy, and simply being incapable.
You wouldn't tell a deaf person that they're just not trying hard enough to hear, otherwise they could. You wouldn't tell a wheelchair bound vet who lost both his legs in the war that he's just not trying hard enough to stand up and walk. You wouldn't call an infant lazy for not picking up William Shakespeare and reciting it from memory.
I suffer from mild depression. I've spent many days and countless nights doing absolutely nothing. I've had a list of things I needed to do, had plenty of motivation to do it, but instead sat around doing nothing. Not because I didn't want to, but because I literally felt physically and mentally incapable of getting up and doing it. I have close friends and family members who suffer from moderate to severe depression that do this more often than not. They are literally incapable of doing something that any outsider would think they should have no problem doing.
There is a difference. A lazy person simply chooses not to fulfill responsibilities. A depressed person simply can't do it. Not everyone is open about their depression. There may be someone you or I have called lazy, or mumbled to ourselves about how lazy they are, when there actually is a psychological problem they're suffering through that makes them incapable of living up to our expectations. Don't be so quick to judge. Just as we are only doing our best with what we have, remember to give others the benefit of the doubt that they're doing their best as well, even if their best seems less than what we think it should be.