If your circulation is poor, it will slow down the blood flow throughout your body, meaning that the cells and organs can’t get the oxygen they need to function as they should.
If you smoke, quit - nicotine is very harmful to your artery walls and thickens the blood so that it can’t reach your body’s key functions.
Cardiovascular exercise can boost the flow of circulation throughout your body, too.
If you’re sitting at a desk all day, take regular breaks to walk around and try wearing compression socks or elevating your legs from time to time, which helps to encourage the blood vessels to pump blood up to your heart.