A black sweatshirt and black sweatpants are the kind of a tested off-duty combination that you so terribly need when you have no time. When in doubt as to the footwear, stick to a pair of black canvas high top sneakers. It's is an excellent idea when it comes to a cool getup that will take you from summer to fall. Those wondering how to rock cool casual style as you go through your 20s, this ensemble should answer your question.