Instagram’s hashtag ‘Sunday fun day’ does not appeal to all and if it does, come a certain hour, much of the developed world gives a collective groan. Even after the best of weekends (or especially after the best of weekends), there’s a cloud that descends. Monday is fast approaching, and the blues set in. What if Sunday remains the lazy day that we know it to be? A day when depression and melancholy slip in, putting you into couch potato…