A black gilet and sweatpants are essential in any man's functional casual closet. If you're on the fence about how to finish, introduce a pair of beige leather low top sneakers to the mix. In the colder months, when warmth is essential, it can be easy to surrender to a less-than-stylish ensemble. This ensemble, however, is a bright example that you can actually stay comfortable and remain stylish in the colder months. This combination shows how to stay stylish as you step into your 30s.