I do my best to believe other people are inherently good; that is, they want to do the right thing. And this is more tightly focused within the context of your particular environment.
I work at a company where we adhere to core values. These values are at the root of everything we do — we hire, fire, and promote based on them. So in the context of my work, I feel confident assuming the best in other people and their intentions.
When I go into a meeting with another person who has said something I didn't receive well, I assume no malcontent, and there was simply a misunderstanding. This is almost always the case.
I'm trying to do this more with other people and, particularly, with my children. My eleven-year-old step-daughter regularly partakes in activities that bring her psyche into question. The phrase "I don't understand." is regularly uttered in our household (by me and my wife). It's become so common, in fact, I think t-shirts — or a massive poster on the wall — would be a more efficient delivery vehicle for the phrase.
Even if the other party does indeed have malicious interests at heart, starting from the assumption that they don't is still the best move. Innocent until proven guilty, right?
The danger in assuming the worst is the story we make up in our heads. We build elaborate labyrinths of lies and misinformation, purely based upon a foundation of speculation and imagination. You can convince yourself of anything if you really want to. And other people and their intentions — rooted deeply in a primal instinct of self-preservation — is no different. We are competitors, genetically wired to stave of extinction.
So don't fight it. Force your brain to assume the best in other people and their intentions, and you can reframe the situation to one where you are in a position of power.