This casual combo of a black crew-neck t-shirt and navy jeans is extremely easy to put together without a second thought, helping you look awesome and prepared for anything without spending a ton of time digging through your wardrobe. When it comes to footwear, go for something on the dressier end of the spectrum and finish off this ensemble with a pair of navy slip-on sneakers. You totally can look easy breezy under the oppressive heat. The proof is right here And if we're talking casual outfit ideas for 40-year-old guys, this outfit suits almost any gentleman.