It’s easy to get caught up in tending to your weight or the look of your biceps — but don’t forget about gains for your brain. “The brain is a part of our body. The same things that create wellness within our body create wellness within our brain,” Dr. Randy D’Amico , director of the Brain and Spine Metastasis Program of Neurosurgery at Northwell Lenox Hill Hospital, told The Post. “The brain is a network of networks. It is important to keep it strong, but it is equally important to replenish