See the listed resources to learn safe stretches designed specifically for computer users. Many can be performed without leaving your workstation. Alcohol causes dehydration, which exacerbates soft tissue injury. It also interferes with sleep. Caffeine allows us to work longer hours without fatigue, straining our limbs beyond safety.
Nicotine interferes with blood circulation, necessary to remove waste products from the bloodstream.
Smoking also replaces oxygen, needed by your muscles, with carbon monoxide. Both obesity and extreme slenderness are associated with higher risk for injury. Women are more susceptible to RSI than men. This may be due, in part, to the higher proportion of women doing repetitive tasks. Women, however, have smaller muscles with which to do the heavy keyboard work.