A white crew-neck t-shirt and dark green sports shorts are veritable must-haves if you're putting together an off-duty wardrobe that matches up to the highest sartorial standards. Channel your inner David Gandy and introduce a pair of slip-on sneakers to the mix. A vivid example of transitional style, this look is a staple come warmer weather. Those who are curious how to rock cool off-duty style as you go into your 30s, this getup should answer your question.