Stretching makes you happy and healthy and supple and flexible...and oh yeah wise!
Right in the middle of your day stand in a doorway ,forearms on each side,lean outward,feel your chest opening and breathing,feel the spaces filling with oxygen,giving you energy!
Take a few deep breaths.Repeat several times a day.
The joy of stretching like this is that it can be done while making supper,(unless you're in a tent with no doors),while watching T.V.,,in the car and even in bed.
The more you stretch the easier it will get.And the more energetic you will feel.