For a neat and relaxed ensemble, reach for a navy and white horizontal striped crew-neck t-shirt and beige sweatpants — these items work well together. You can get a little creative when it comes to footwear and complement this look with brown leather desert boots. These picks will keep you comfy and stylish in unpredictable fall weather. This getup should clear any doubts you had about dressing casually as a gentleman in his 40s.