When things got stressful at work I started smoking cannabis daily. It was really detrimental to my overall productivity. It was great for the stress, and made me feel wonderful, but it’s severely dulled the sharp edges of my mind.
Then I went to the mall high with a sober friend - and had to keep him from getting distracted in stores and keep him on track to buy the item we needed. That's when I realized I was High-functioning. (True stories.)