A long sleeve shirt and olive cargo pants paired together are a sartorial dream for guys who prefer casually cool styles. A pair of dark brown leather casual boots will lift up any look. During the colder months, when functionality is paramount, it can be easy to surrender to a less-than-stylish outfit in the name of functionality. However, this outfit is a bright example that you can actually stay cozy and remain equally stylish in the colder months. This outfit should clear any doubts you had about wearing casual clothes in your thirties.