I like the title of your thread. :)
At first glance, the room is very beige-y and angular. Can you paint? White walls, or maybe a light grey will perk up the room a lot since there's only that one window. And even though you rent, can you take down the vertical blinds and hang patterned curtains anyways? Just re-mount the blinds when you move out? Is there a way to camouflage the blinds with curtains? Vertical blinds are really gonna kill any zen you hope to achieve. :)
If the TV is going into a closet, then definitely get rid of the stand that it's on. It's too big for the room. (All the furniture is on the large side for a narrow room.) I'd look for an oval coffee table to replace the square one. The round edges would soften the room, with the bonus of being easier to move around! Or a upholstered ottoman.
More art work, and a large ass mirror to reflect the light that's coming in, either over the couch or above the tv spot. I'm a big fan of house plants. Look on Pinterest for inspiration. Try and get a mix of sizes - small succulents, a hanging pot, a potted indoor tree, etc. I get all of my planters and pots from the thrift store.
You could also set up a reading corner by the window, or in place of the TV. Wing chair, table lamp, side table, wool blanket. Serenity!