Take Some Time
Your blood is filled with all kinds of proteins and antibodies that you need for energy. So, when there is some that is drawn from your system, your body needs some time to adjust. It's a good idea to wait a couple of hours to listen to how your body is responding to the procedure. If you feel lightheaded or dizzy, that a surefire flag that pushing your body further is not the best thing to do.
Honestly, it's smart that you make sure that you eat a healthy meal the night before as well as the morning of having your blood drawn. Among all of the things that you can add to your diet, iron-rich foods are the most important because a lack of iron is usually what brings about the woozy kind of side effects that come with having blood drawn. Iron-rich cereals and fruits like raisins, apples and strawberries are all good options. Once you have had your blood drawn, in order to replace the fluid and iron that you lost (especially if you were actually donating blood), try drinking some grape juice or eating a salad or a meal that has chicken breast or salmon included with the entrée.
Ease into Exercise
According to the Red Cross and many other comprehensive health test panels, if you had blood drawn to donate in order to save someone's life, you need to wait approximately five hours before engaging in any form of strenuous exercise. If you simply gave blood, wait a couple of hours and still try and keep it light for the remaining part of the day. You probably should avoid doing any kind of heavy cardio or weight lifting but you can do things like yoga, Pilates, walking and some mild cycling. The main thing to keep in mind is that our bodies are made in remarkable ways. When something is not quite right, it will usually send signals to let us know. So, if you start exercising and you find that you don't quite feel like yourself, drink plenty of fluids, lay down a bit and try again the next morning. If you're still uneasy, it's best to notify your physician. Remember, exercise is to make you feel better, not to cause further complications. After having blood drawn, ease into exercising; don't force it.