Answer:
Here's a couple of reasons:
not doing enough physical activity
being too sedentary, e.g., sitting or lying down for long periods
having an unhealthy diet, e.g., eating too much or too little, eating too much fat/sugar/salt
not getting enough sleep or having erratic sleep patterns
smoking
abusing alcohol, example: drinking too much and/or too often
Step-by-step explanation:
Hope this helps you!!!