Get more done less stressfully by doing one thing at a time.
You can do anything, but you can’t do everything. Not all at once, at least. Multitasking may not be a as complete fallacy (as some claim), but the typical kinds we think of when somebody talks about it - those kinds are a bad idea. Multifocus is generally bad. Have one thing. Know Your Immediate Task.
Working intently on one thing at a time (until you’ve hit a natural pausing point) is the key to doing high quality, low stress work.
You cannot have a breakthrough on something while thinking about something else. Juggling several tasks at once leads to poor performance on all of them, burnout, and undue stress.