This pairing of an olive cable sweater and beige chinos is hard proof that a simple off-duty outfit doesn't have to be boring. If you wish to instantly dress up your outfit with shoes, introduce a pair of dark brown leather brogues to the mix. On not so cold days, you can rock this easy-to-transition outfit and look absolutely awesome. This ensemble is probably what you're looking for as a 30-something Millennial gent.