For an outfit that's very simple but can be worn in many different ways, consider teaming a navy crew-neck t-shirt with blue chinos. In the shoe department, go for something on the relaxed end of the spectrum by finishing off with a pair of white and black athletic shoes. A cool ensemble like this one is just what you need come baking hot sunny days. Off-duty ensembles for mature gentlemen aren't actually that hard, as you see.