Wear a white crew-neck t-shirt and dark green sweatpants for an easy-to-wear outfit. When not sure as to what to wear on the shoe front, add a pair of white athletic shoes to the mix. And if you're scouting for a kick-ass look that will take you from winter to spring, look no further. Wondering how to perfect casual outfits as you mature into your 30s? This pairing is a great illustration.