Cast iron skillet iron leakage
The amount of iron that you need is going to depend on your age, sex, and health.

NIH: Iron Fact Sheet
WebMD: Iron: What you Need to Know
Having indicated that you work out, you may need more than you think, but you are wise to be concerned about having too much. A typical adult male only needs 8mg. How much iron is leeched into the food your cooking depends on what you are cooking -- and how old your pan is. Acidic foods like tomatoes and (for some reason) applesauce seem to demonstrate this more than other foods. But I disagree with nutritionovereasy.com's indication that food cooked in the pan will aquire a metalic taste (see link below). I've never had that happen.
Do You Absorb More Iron Cooking in a Cast Iron Pan?
Cast Iron Pans can Increase Your Iron Intake
Learning how to handle Cast Iron is a worthwhile endeavor. You can start a dish stovetop and slide it right into the oven. Some of my favorite recipes use the same skillet I've been cooking with for more than 3 decades. Here's one more link to get you off to a good start: America's Test Kitchen: Cook It In Cast Iron.