While there are many philosophies and methods out there today. This is what I have found to be most effective over 3 decades of application.
Importance of breathing when lifting weights. It ensures that the blood circulating to your working muscles is oxygenated and that waste products are removed. Holding your breath during weight lifting can lead to dangerous increases in blood pressure, which can lead to injury. Use your breath for you, not against you. i.e. When you do a bicep curl and bring up the dumbbell, breathe out.
When you lift weights, you build lean muscle tissue which is more metabolically active than fat. When you increase your muscle, you also increase metabolism which means you're burning more calories throughout the day. Regular strength training is just as important as cardio exercise for losing fat and getting fit. Utilizing a target weight for your desired number of repetitions leads to optimum development and performance.
One of the most important reasons to maintain proper form during weight lifting exercises is to prevent injury. When we lift a lot of heavy weight, this can cause the body to become misaligned that can place your tendons, muscles and joints in positions that can potentially cause strains or tears.