This combination of a navy and white horizontal striped crew-neck t-shirt and navy jeans is a safe go-to for an effortlessly cool outfit. For a smarter touch, add brown suede desert boots to the equation. Can you see how super easy it is to look stylish and stay warm when chillier weather arrives, all thanks to ensembles like this one? All in all, an ideal example of casual style for gents in their forties.