Bones can weaken due to osteoporosis, aging, lack of calcium, poor diet, or lack of exercise. Osteoporosis occurs when bones lose density, making them brittle and prone to fractures. Consuming calcium through food and supplements along with vitamin D, eating fruits and vegetables, and regular exercise can help strengthen bones and reduce the risk of osteoporosis. Osteoporosis increases the risk of bone fractures which can impair mobility and lung function if the spine is affected.