A blue blazer looks especially good when married with a crew-neck t-shirt in a laid-back ensemble. To add a hint of stylish casualness to your outfit, add a pair of white low top sneakers to the mix. This combination is a vivid example 40-year-old gentlemen can very well kill in the fashion department.
You'll be surprised at how extremely easy it is for any man to put together this casually classic look. Just a blue blazer and a crew-neck t-shirt. Take your getup in a more casual direction with white and navy athletic shoes. This getup should clear any doubts you had about dressing casually as a middle-aged man.