Try teaming a v-neck t-shirt with jeans to create an extra dapper and modern casual outfit. Got bored with this outfit? Invite white canvas slip-on sneakers to spice things up. Keep this outfit in your front hall wardrobe when spring sets it, and we promise you'll save a lot of time trying to pick out a look on more than one occasion. When it comes to casual outfit ideas for gents in their 40s, this outfit suits almost any guy.