▶ 00:07Troy's princess, Cassandra, wasn't cruel to her soon-to-be sister-in-law, the legendary beauty Helen, out of spite. It was because she was suffering under the weight of a tortuously twisted curse, which haunted her with appalling visions linked to Helen's arrival.

▶ 00:25Helen was already married to the Spartan king Menelaus, after all. And when Cassandra's brother, Prince Paris, prepared to sail to Sparta, she foresaw his calamitous attachment to Helen and begged him to stay. But he'd merely dismissed her, fallen for Helen, and returned to Troy with her in tow. Beset by violent premonitions, Cassandra then warned that Menelaus' vengeful crusade would lead to the brutal fall of their family and the city of Troy. But once again, people ignored her.

▶ 01:00In fact, they always did. And this was the crux of her curse. As a young woman she had been pursued by the god Apollo. He offered her the gift of prophecy. But when she withdrew from his advances, he twisted his gift into a maddening hex: from that day on, Cassandra would be able to precisely see and describe the future— but her prophecies would never be believed. Despite this, Cassandra resolved to always speak the truth, even as her family fell deeper into denial.

▶ 01:36Her dire warnings became increasingly repellent to her father, Trojan King Priam. And when the war began, as she'd predicted, he declared that her meddling was bad for morale and confined her to a high tower. From this unobstructed lookout, Cassandra watched everything unfold. Over 10 agonizing years, she witnessed her own grisly visions of senseless destruction come to pass on the battlefield below.

▶ 02:04When dawn broke one day to reveal a huge wooden horse in place of the Greek encampment, the Trojans believed that the victory had finally been secured. Their enemies appeared to have fled, leaving this inscrutable token of peace behind. But as others streamed into the streets to celebrate, Cassandra realized the insidious truth.

▶ 02:27Brandishing a battle-axe and a flaming torch, she descended from the tower and ran at the wooden horse, alerting everyone that it was a trick. Instead of heeding Cassandra's warnings, they wrestled her to the ground and scoffed that she was getting more paranoid with age, then proceeded to tug the behemoth gift horse inside the city's walls.

▶ 02:48As Troy fell into an oblivious slumber that night, Greek soldiers descended from the wooden horse's belly. All had gone according to plan, and they scattered among the city streets, intoxicated with their victory, to unleash a torrent of pent up, violent chaos.

▶ 03:06Cassandra had seen her city burn and heard her people's screams many times, but that didn't make the reality any easier to bear. Her nightmare had come to pass. As dawn neared, the commander of the Greek army, Agamemnon himself, arrived to claim Cassandra as his prize. He dragged her back to his ship, boasting relentlessly of his victory as they set sail. But Cassandra told him plainly that he'd be punished. Earlier in the years of battle, Agamemnon had sacrificed his daughter to the war effort, hoping the gods would favor the Greeks in return. Now Cassandra saw that his wife, Clytemnestra, awaited his return, poised for revenge. But just as certainly as she saw that Agamemnon was sailing towards his own murder, Cassandra saw that she would also be killed in the fallout.

▶ 03:59As always, she confronted the grim fate. In her lonely pact with the truth, no matter how ugly, Cassandra had always stood apart. After all, was it not her but everyone else who had fallen victim to the curse, living in deceit's shadow, oblivious to reality until the bitter end?

▶ 0:06Muscles. We have over 600 of them. They make up between 1/3 and 1/2 of our body weight, and along with connective tissue, they bind us together, hold us up, and help us move. And whether or not body building is your hobby, muscles need your constant attention because the way you treat them on a daily basis determines whether they will wither or grow.

▶ 0:31Say you’re standing in front of a door, ready to pull it open. Your brain and muscles are perfectly poised to help you achieve this goal. First, your brain sends a signal to motor neurons inside your arm. When they receive this message, they fire, causing muscles to contract and relax, which pull on the bones in your arm and generate the needed movement.

▶ 0:53The bigger the challenge becomes, the bigger the brain’s signal grows, and the more motor units it rallies to help you achieve your task. But what if the door is made of solid iron? At this point, your arm muscles alone won’t be able to generate enough tension to pull it open, so your brain appeals to other muscles for help.

▶ 1:13You plant your feet, tighten your belly, and tense your back, generating enough force to yank it open. Your nervous system has just leveraged the resources you already have, other muscles, to meet the demand.

▶ 1:27While all this is happening, your muscle fibers undergo another kind of cellular change. As you expose them to stress, they experience microscopic damage, which, in this context, is a good thing. In response, the injured cells release inflammatory molecules called cytokines that activate the immune system to repair the injury. This is when the muscle-building magic happens.

▶ 1:53The greater the damage to the muscle tissue, the more your body will need to repair itself. The resulting cycle of damage and repair eventually makes muscles bigger and stronger as they adapt to progressively greater demands. Since our bodies have already adapted to most everyday activities, those generally don’t produce enough stress to stimulate new muscle growth.

▶ 2:17So, to build new muscle, a process called hypertrophy, our cells need to be exposed to higher workloads than they are used to. In fact, if you don’t continuously expose your muscles to some resistance, they will shrink, a process known as muscular atrophy. In contrast, exposing the muscle to a high-degree of tension, especially while the muscle is lengthening, also called an eccentric contraction, generates effective conditions for new growth.

▶ 2:46However, muscles rely on more than just activity to grow. Without proper nutrition, hormones, and rest, your body would never be able to repair damaged muscle fibers. Protein in our diet preserves muscle mass by providing the building blocks for new tissue in the form of amino acids. Adequate protein intake, along with naturally occurring hormones, like insulin-like growth factor and testosterone, help shift the body into a state where tissue is repaired and grown.

▶ 3:16This vital repair process mainly occurs when we’re resting, especially at night while sleeping. Gender and age affect this repair mechanism, which is why young men with more testosterone have a leg up in the muscle building game. Genetic factors also play a role in one’s ability to grow muscle. Some people have more robust immune reactions to muscle damage, and are better able to repair and replace damaged muscle fibers, increasing their muscle-building potential.

▶ 3:44The body responds to the demands you place on it. If you tear your muscles up, eat right, rest and repeat, you’ll create the conditions to make your muscles as big and strong as possible. It is with muscles as it is with life: meaningful growth requires challenge and stress.