Stretching can feel good because it changes how your body senses tightness, tension, and discomfort. It may temporarily reduce stiffness in muscles, tendons, and nearby nerves while also making your nervous system more tolerant of the stretching sensation.
Research suggests that stretching can briefly make people less sensitive to pressure-related pain, both in the area being stretched and sometimes elsewhere in the body. Over time, regular stretching may also increase how much tension you can comfortably tolerate, which can make movement feel easier and less restricted.
The pleasant feeling does not seem to come from one single process. Changes in tissue stiffness, stretch tolerance, and the way the nervous system processes discomfort may all contribute. Possible effects on relaxation and the autonomic nervous system have also been studied, but the evidence for these effects is still limited.
You do not need to stretch until it hurts to get these effects. Stretching to a comfortable level of discomfort appears to provide similar short-term changes in pain sensitivity, so avoid forcing a stretch or pushing through significant pain.