What are the beneficials hormones released during weight lifting?

Endorphins:

“Many studies show that people who exercise regularly benefit with a positive boost in mood and lower rates of depression.

Improved self-esteem is a key psychological benefit of regular physical activity. When you exercise, your body releases chemicals called endorphins. These endorphins interact with the receptors in your brain that reduce your perception of pain.

Endorphins also trigger a positive feeling in the body, similar to that of morphine. For example, the feeling that follows a run or workout is often described as ‘euphoric’. That feeling, known as a ‘runner’s high’, can be accompanied by a positive and energizing outlook on life.

Endorphins act as analgesics, which means they diminish the perception of pain. They also act as sedatives.”

All your chemistry improves during serious exercise—not only while you’re doing it, but long after you’ve left the gym. Your body simply becomes a much more efficient machine.

As stated above by @Brian46, endorphines flow. Seratonin flows and improves one’s feelings of well being and ability to handle stress remarkably. Oxytocin flows, and combined with other chemistry, puts you in what athletes call the “zone,” a near hypnotic state where you can do no wrong, make instant decisions on a subliminal level, and time flies. After a month of working out every few days—either running, biking, rowing, climbing, brisk walking, lifting, any sustained positive stress on your body—you get to the point where your day isn’t complete without your workout; your mood is affected.

Endorpnines may allow you t go beyond the immediate discomfort of the work out by raising your pain threshhold and making you feel like you can walk through walls, even mildly aggressive, more assertive when you need to be. But the Oxytocin compensates by making you feel sexier, more cuddly, friendlier. It also makes you more interested and curious about the world and people around you. And when you feel sexy and happy and interested people react positively to you, because they would rather be around a happy person than a constant buzz kill. You may think it’s because you’re a little more ripped now, that there has been this amazing physical transformation, but after only one month? Nah, not much.

The Seratonin makes you more confident, self-assured, allows you not to sweat the small stuff. The endorphines numb you to the minor physical discomforts in life, you’re more tenacious and and have a much better balanced fight-or-flight instinct (anabolic steroids totally fuck this up). The Oxytocin makes you feel sexy and people react to this and find you more likeable and you become more willing to recieve intimacy. With a combination like that working for you, life goes from a mysterious box of chocolates to a very interresting bowl of cherries. After a few months, as a mere side-effect, the image in the mirror changes, and the person you’ve released has a body to match.

You shouldn’t discount a yoga combined with meditation as a way to accomplish the same improvements in your body chemistry and that yoga is an excellent and effective way for people with range-of-motion restrictions and other limitations to do so. Yoga breathing techniques alone, especially Ujai, or Ujjayii Pranayama, which has shown remarkable results in improving the lives of PTSD patients. It’s not called the Breath of the Conqueror for nothing. It is very powerful stuff, these pranas.

So, why are yogis, runners, gymrats and most athletes in general seemingly way too happy and confident most of the time? Now you know.

Let’s just say If I go more than a couple of days without my runner’s high I start to get cranky. While exercise is good for you the feel-good effects are temporary. Reducing stress levels and living a more balanced life is more important. (I’m not there yet but working at it)

Edit paragraph 5 above:

“You shouldn’t discount a yoga combined with meditation as a way to accomplish the same improvements in your body chemistry and that yoga is an excellent and effective way for people with range-of-motion restrictions and other limitations to do so.”

Should read:

You shouldn’t discount a yoga breathing techniques combined with meditation as a way to accomplish the same improvements in your body chemistry, The Yogic prana are most effective for people with range-of-motion restrictions and other limitations such as cardiac or pulmonary deficits to accomplish this.

In other words, the pranas are a way for people who cannot go to the gym or persue other activities to obtain and retain good general health and a feeling of well-being.

Addendum:
Besides the throaty Ujai breathing technique as referenced above, the Nadi(yoga) in the morning is very effective for reducing anxiety, eliminating insomnia (and thus lowering high blood pressure in hypertensive patients) and—if practiced regularly—maintaining optimal homeostasis, or good, balanced general health. Both Ujai and the Nadis can be done in the Death Pose or Shavasana (my favorite) and require no yogic contortions whatsoever.

The simple Nadi Shodhana (alternate nostril breathing technique) is a rest and revitalization tool and is very effective against insomnia. If you’re having trouble sleeping, lie in bed and begin the Shodhana and you will be asleep within a few minutes. In tense situations, before an important job interview or a day on the witness stand, or after a car wreck, a few minutes of Shodhana in a bathroom stall will reduce anxiety to near-normal levels. Regular Shodhana practice will guarantee deep sleep and anxiety-free days.

There is no magic or religion in any of this. Empirical evidence, such as before-and-after blood draws on PTSD patients, have shown the same marked improvements in body chemistry as athletes after a short time. It’s just 5,000 year-old medicine. It’s cheap—after a short period under a good teacher, you carry your medicine with you all your life—and there are no stupifying medications or troublesome side-effects to deal with.

Here is a list of other healthful breathing techniques.

These aren’t chemicals but as for body effects I would like to add improved and effiecient digestion higher metabolism as well as better circulation.

Thanks @Espiritus_Corvus I am def going to try the nadi shodhana. Just what I needed as my situational insomnia won’t even subside with sleep meds which I resorted to after I was switched to meds that require me to take them at night and me be asleep but also prevent it.