Although blood is truly necessary for life, only about one in 20 persons will donate blood for use by others who are undergoing surgery, being saved after accidents, or require blood components because of some chronic condition. The most common reason for not donating appears to be a fear or dislike of having a needle inserted into a vein in the arm. I don't really enjoy it either. But then I don't enjoy the thought of a person, caught in a bad situation through no fault of his or her own, dying because needed blood wasn't available. So, if you are already a donor, you can help greatly if you schedule a second, or other additional donation.
Most persons can donate blood.
There is no age limit and no discrimination between the sexes. Yes, some persons should not donate, based on their health history, prescriptions they take and other factors. The Red Cross makes vigorous efforts to insure that the blood supply is safe by asking a number of questions, checking to insure that a donor is well and healthy at the time of donation, and giving each donor several chances to withdraw from donating gracefully if there is even a slight possiblity that a donation should not be used. If you qualify, then they can tell you the local number to call for a donation appointment. Blood donations can be made at various headquarters sites or at sites visited by mobile teams that operate in different places each day.