When I try to donate blood or have to have lab work done it is very hard to find my vein. I have been told that I have "bad veins". What exactly is that and is there anything that I can do to improve my veins?

You don't really have bad veins , per say,they are just using that term as a description. When what they are trying to tell you is that your veins are deep in your tissue and they may roll a lot. When the nurse or tech is trying to draw blood. That does not mean you have a problem your circulation in the veins is probably fine.. don't worry about it.