I remember asking a meditation teacher: Does a cat generate bad karma by killing?
I expected the answer: No, it's just his instinct. He has no choice.

But instead he slightly smiled and said something like `It's hard to get out of being an animal'

It's easier to make money when you already have a lot.
It's easier to generate good karma at moments when you are experiencing the pleasure of previous good karma.

But when you are not. And you are looking around, envious. Why did he get the relationship he wanted?
Why did he get the job he wanted?
You find yourself wanting to be bitter.Wanting to be the victim and tell yourself how everybody uses and mistreats you.
You find yourself cutting people on the road. Not stopping when a mother with her baby wants to cross.
You have a day where you feel as miserable as you did as a teenager.
No hope, only darkness.
You go get some coffee to help you finish some work.
Or perhaps, you think of some work you need to finish to have an excuse to drink more coffee.
Especially soy-milk capuccinos can be watery and tasteless if not done right.
But you get a cup that is thick and tasty.
You wait for a second for the guy to end a phone call and say
`You guys always make the best coffee around!'
You feel better than you did all day.
For a moment, you are not poor or envious.