Downplay the pain that others feel because it doesn't look so bad from where you're standing.
This is a hard one to describe. It's not necessarily about actively minimizing and downplaying the pain that others have to deal with, rather it's about learning to recognize that someone else may be dealing with a different set of problems that you face.
The problem with news stories (and yes, this is a bit of a diversion from the actual point of the post) is that we only see a small part of the story. Part of this is on purpose; News organizations sell stories much better if they sensationalize them. Giving the full story usually downplay's the "outrageousness" of the situation that gets eyes on their pages.
You'll usually read headlines like "Student expelled for [insert act that seems completely harmless on the surface]". Your immediate reaction: "WHAT?! How can they expel a student for wearing a rebel flag t-shirt?!" Hook, line and sinker, the news story has got you. In reality, the story is much deeper and actually has a sane & rational explanation, but that's not what the headline reads.
Relating this back to productivity, too often we catch ourselves minimizing complaints made because we don't understand the full story. If you find yourself asking "Why can't this person just use Tool X like the other employees at the company?", think about the situation that the other person is in. Are their circumstances or requirements different from others? When they say that this tool is awful, and you've had nothing but success from it, chances are they're using it in a completely different way than you are.
Why is this a productivity thing? Well, when you spend your days arguing why something isn't really all that important (instead of spending that time to figure out why it is important), you spend your days wasting time. Even if you think it's a waste of productivity to do things a different way, chances are if someone is really passionate about it, it's for a good reason. It may be a waste of time for you to change over to something different, but it may drastically improve the productivity of someone else. Don't deny alternatives simply because you don't see the need for them. Accept that people are different, have different needs, and therefore need different solutions.
The real challenge is to take this a step further. A lot of times people will see changes that could be made to improve their productivity but won't say anything because they know others aren't affected by it. Chances are they won't say anything because they know they're unlikely to convince someone who doesn't feel their pain. Many hours will be wasted having a person struggle with something simply because their pain wasn't shared.
It's your responsibility to step outside of your comfort zone and get to know the pain that others feel. Pain (and the want to avoid it) is a great motivator, so step out of your own comfortable shoes and into the painful ones others wear. You may just figure out why they're complaining so goddamn much.