u/ITburrito

I know I ought to be happy and appreciative every moment, because I’m not going to live forever. And yet I can’t help being anxious, depressed, miserable. Why can I not be happy just because I am?

I’ve heard I can use "If I were" when talking about an imaginary situation. But does the same apply to "unless"? Can I say "unless I were" to speculate about something that wouldn’t happen except for particular circumstances (like in the example in the title)?

I work for an IT company in an international team, so we communicate using English in order to understand one another. None of us is a native English speaker, though, and sometimes I feel like some phrases we use are outright made up. For instance, whenever there’s a task or a problem we nee to deal with, the managers will reach out to someone and say either"Please take it in hand" or "Please take in hand".
Is it something native speakers would say or at least understand? Is this a common phrase in English or is it a novelty that emerged from imperfect English skills?