If possible, have a sheletered space. Both of these examples offer some shelter from the elements, so they'll be warmer even in winter. These "before" pictures serve as a reminder that fresh paint will brighten up an outdoor room just as they do an indoor room.
If you rely on flowers and greenery for the decor during the warmer months, have a back up plan for the winter. Bring out cushions and throws to add a pop of colour. Strong textures like Aran knitted afghans or plush throw pillows feel warm and look great.
Think about a fire put or outdoor fireplace, too. Some literal warmth combines with the warmth of wool and soft furnishings to make a welcoming space.
After a morning run or a long day at work, a hot drink on a balcony or a hot meal by the sparkling pool can be just as pleasurable as a cool drink in the summer.