Go for a straightforward but at the same time cool and casual option by putting together a black turtleneck and grey jeans. A pair of white leather low top sneakers is a savvy pick to finish this outfit. Casual getups for 30-something Millennial men aren't actually that hard, as you see here.
If you're planning for a sartorial situation where comfort is everything, team a black turtleneck with grey jeans. To give your overall outfit a sleeker finish, add black leather casual boots to the equation. Ideal if you're looking for some amazingly inspiring laid-back style for 30-something Millennial men.