I'm going to leave my work high and dry
Why are you going to leave work so suddenly?
I understand my work is highly important but I need to take a break.
It sounds like you have a lot on your plate. It is fine to take some time off of work to recharge now and again as long as your performance doesn't suffer.
I'm going to close my PC and head out for a 15 minute break.
That sounds like a good idea. Sometimes it better to just take a break for awhile.