You are very tired after a busy day, and you feel very happy when you finally get off work. This feeling is caused by endorphins.

You played all day, and you were happy. It's time for bed, but you haven't finished yet. This feeling is caused by dopamine.

So when you exercise for a long distance, it is endorphins that produce new pleasure.

Extended data:

1, dopamine: It is a neurotransmitter, a chemical used to help cells transmit pulses. This brain secretion is related to people's lust and feelings, and it conveys information of excitement and happiness.

2. Endophenolphthalein is an endogenous morphine-like biochemical compound hormone (secreted by pituitary gland). It is an amino compound (peptide) secreted by the pituitary gland and hypothalamus of vertebrates. It can combine with morphine receptor to produce the same analgesic effect and euphoria as morphine and opioids. Equivalent to natural painkillers. The use of drugs can increase the secretion of endorphins.

References:

Encyclopedia _ Dopamine? Baidu Encyclopedia _ Endorphins