Passive voice isn’t inherently a bad thing, and I don’t think it’s a sign of laziness.
If the emphasis is on the action and not on the actor, as is often the case in science writing, passive voice is not only useful and accepted but correct. The reason it’s such a bugbear for writing teachers is that the same thing expressed in passive voice and in active voice is often clearer and more straightforward in active voice. Business writing tends towards the self-important and needlessly verbose, and the use of passive voice when active voice would be terser is one of the most common things that bad writers to to puff up their verbosity.
To identify it, look at each sentence, and ask, is the subject of this sentence the actor (the person doing the action) or the action? One big hint is that you can’t identify the actor—the difference between “I made a mistake” and “A mistake was made.” In the former, in active voice, the subject of the sentence is the actor – I – while in the latter, the subject of the sentence is the action – a mistake. In the latter sentence, you can’t even identify who made the mistake.
But more importantly, focus on omitting unnecessary words. When you write a sentence, look at it and ask yourself, “can I say the same thing more clearly, with fewer words?” If the answer is yes, then do so. You’ll find that your active/passive problems quickly disappear.