This off-duty combo of a navy and white crew-neck sweater and navy jeans is a fail-safe option when you need to look cool and casual but have no time. Why not complement your look with a pair of work boots for a hint of stylish casualness? This ensemble is a bright example you can still look seriously stylish while bundled up. This getup should erase any doubts you had about wearing casual clothes as a 30-year-old gentleman.