Monday 21st January is “Blue Monday”. According to a complicated (and somewhat dubious) formula the third Monday of January is apparently the bleakest day of the year, the one where we feel at our most gloomy and least resourceful. It’s down to a combination of post-Christmas blues, a shortage of cash after seasonal overspending, the premature failure of New Year resolutions and the colder, darker nights. Put like that, they may have a point. If your colleagues at work seem…