Don't try to learn.
"Results are always worse when you multitask, but in some areas they're especially compromised," says Russell Poldrack, PhD, associate professor of psychology at UCLA. Learning takes a big hit, for instance. "Our research shows that if you try to master something while splitting your attention, brain activity switches regions—from memory building to short-term habit making," he says.
A good rule of thumb is to multitask what you want to execute, rather than absorb, and choose jobs where mistakes won't matter.