Half a month ago, my arm ached for 2 days after I finished fitness exercise. Now the same amount of exercise, why didn't my arm hurt the next day?

At the beginning of exercise, muscle pain is due to lack of oxygen and lactic acid production.

Now that your amount of exercise has adapted, he won't hurt, and he has exercised, so it won't hurt!

Exercise can only be effective if you persist, but you should also practice. You should feel that your body needs to customize your exercise plan and don't overload it. If the load is exceeded, it will be counterproductive.

Exercise every day, but the nutrition should be enriched every day, so that the body can absorb it well and it is good for the body.