There are many aspects you can change about your physical health and, consequently, your lifespan. Eating well and exercising can help keep you slim, resistance training will strengthen your muscles, and both of these factors will help you to live longer. But some aspects of your physiology, like your height for example, are harder to change. While you might not think that this would have much of an effect on your health or longevity, the science shows that a shorter height could mean a longer life.
The link between height and lifespan
Researchers have always been interested in how height impacts health and other aspects of life. Studies in the early 20th century indicated that taller people lived longer, but these were confounded by the fact that height is partly determined by how much nutrition you receive during childhood. People who were under-nourished in childhood were more likely to be in a lower socioeconomic class and therefore lived shorter lives. Thankfully the general standard of nutrition is far better now and, although the link between prosperity and lifespan does still exist  (as does the association between height and income ), we can now account for the effects of socioeconomic status. Using new and sophisticated techniques, more recent studies have in fact proved that the shorter you are, the longer your expected lifespan.
A 1992 study found that men who were 5’ 9” (175.3 cm) or below lived roughly 5 years longer than those who were above that height, and men who were 5’ 7” (170.2 cm) or below lived roughly 7 years longer than those 6’ (182.9 cm) or taller.  A recent large-scale analysis found that each added inch in height increased the risk of death by 2.2% and 2.5% for men and women, respectively, and increased the risk of cancer by a massive 7.1% and 5.7% respectively.  Another study found that even among former basketball players (perhaps the tallest study group you could find!) the shorter ones outlived the tallest. 
The effect seems to be slightly more pronounced in men, but it is seen in women too. For example, a recent study showed that taller postmenopausal women are more likely to develop cancer, with a 13% increased risk for every 10 cm increase in height.  In fact, some researchers have proposed that the close inverse relationship between height differences and life expectancy in both genders (men were 7.8% taller and their life expectancy was 8.4% lower) shows that women’s shorter stature is a major contributor to their greater overall longevity.  The same even goes for animals, with smaller members of the same species tending to have longer lifespans. 
Reasons why fewer inches means more years
While the data are pretty clear that a shorter height means a longer life, researchers aren't exactly sure why that's the case. A number of theories have been proposed:
- Shorter people require less nutrition and, as calorie restriction is a well-established method for extending lifespan, this may cause them to live longer.
- Taller people have more cells, which means more damage by free radicals and carcinogens, increasing the risk of cancer. More cells also means more cell replications, which increases the risk that a cell may mutate and become cancerous.
- Some have suggested that the growth hormones that cause increased height may also increase the risk of cancer.
- One study found that shorter men were more likely to carry a variant of the FOXO3 gene that causes decreased size but increased lifespan. 
- Some evidence suggests that the lungs of tall people do not function as efficiently, and respiratory disease is particularly associated with increased height. 
- The taller you are, the more weight that is carried in the vessels taking blood from the heart to the rest of the body, which may cause the increased rate of blood clots suffered by taller people.