Showcase your credentials in men's fashion in this relaxed casual pairing of a navy and white vertical striped blazer and a white crew-neck t-shirt. For something more on the casual side to complete this getup, complement this look with a pair of black and white canvas low top sneakers. Undoubtedly, it's easier to work through a baking hot summer day in a cool look like this. This combo suggests how to keep killing in the casual fashion department as a 40-year-old.