Any exercise can lead to the release of endorphins. Endorphin release doesn't occur only to mask the damage you are doing to yourself in the face of an extreme life threatening situation (which is also accompanied by the release of adrenaline and other hormones).

>The endogenous opioids seem likely to be assigned a significant role in the integrated hormonal and metabolic response to exercise. This article reviews the present evidence on exercise and the endogenous opioids, and examines their involvement in a number of widely disparate physiological processes

http://www.ncbi.nlm.nih.gov/pubmed/6091217