Go for classic style with a white and navy crew-neck t-shirt and grey dress pants. Why not take a more elegant approach with footwear and complete your outfit with a pair of loafers? Like this outfit idea for a gentleman over 40?
White and Navy Crew-neck T-shirt with Loafers Dressy Outfits For Men After 40
For a look that's worthy of a modern style-conscious guy and casually neat, try pairing a white and navy crew-neck t-shirt with charcoal dress pants. You can go down the classic route on the shoe front by rounding off with a pair of loafers. This combination is most probably what you're looking for as a guy in his 40s.
Infuse a sense of casual sophistication into your current collection with a white and navy crew-neck t-shirt and a navy suit. Take this ensemble down a classier path by sporting a pair of loafers. This is a nice yet age-appropriate getup for middle-aged guys.