For example, ATC might give an altitude restriction for safety: “Cessna 123AB, maintain VFR at or below three thousand for crossing traffic.” Observing this restriction is important, but staring at the altimeter will likely result in the heading wandering all over the place and ironically even a tendency to over-control altitude that may cause wandering up and down. The proper way to execute it is to learn what the level sight picture looks like, put the nose there, trim for straight-and-level flight, and occasionally peek at the altimeter and VSI to confirm that it’s staying there. If the pilot gets distracted, say looking down at an iPad for a bit, look outside first to get back on heading if necessary, check the instruments (“take a picture with your mind”), and make small adjustments to get back to where it should be.
ATC operates on lots of buffers. For a restriction of three thousand, that crossing traffic is likely to be at 4,000 or higher.
Look outside, and learn what correct looks like. References on the ground are already giving you gobs of information. The feel of the yoke and the sounds from the engine are also giving you continuous clues about what the airplane is doing. No sim I’ve seen reproduces all of those additional channels of information.
Where simulators are really helpful is with procedural flying, like practicing instrument approaches. You can’t log your desktop sim for currency, but advanced training devices are good enough in the FAA’s eyes.
You’re generally operating well away from a perilous state with ample margins of safety. I find flying incredibly relaxing.