Downward facing dog aka Adho Mukha Svasana. Re-invigorates the person who has settled into a slouch. Enlivens the gaze. Practice for at least five minutes after 4 hours of sitting. Ok to play with it, go into Wild Thing or whatever variation makes you happy. Try getting around on all fours--feet and hands, no knees. The dog knows how. The heart is the center for this asana.