If you're looking for a casual and at the same time on-trend ensemble, try pairing a navy shawl cardigan with dark brown jeans. Introduce loafers to the equation for a masculine aesthetic. Now that's an ensemble any gentleman in his forties will appreciate.
If you appreciate the comfort look, wear a navy knit turtleneck and dark brown jeans. And if you want to effortlessly spruce up this ensemble with a pair of shoes, why not complement your look with a pair of loafers? Certainly a savvy idea if we're talking outfit ideas for over-40 gents.