Congrats on wanting to tackle an Ironman! Triathlons are great for mental and physical training diversity and the health benefits far outweigh the possible negative effects of a hard training schedule. Preparing for an Ironman really depends on where you are currently with your fitness. The number one thing to remember is to only increase your training load ~10% each week (load can be distance, intensity, or both) and to have "down" weeks every 3-5 weeks. It's hard to train for an endurance event without having some body niggles - have a physical therapist and/or massage therapist can help you recover from your work-outs better and allow you to train to your potential. I am a marathon runner, a running coach, and participated in several triathlons of various distances. Each training cycle has looked different depending on the time of the year, my base fitness level, and my goal. Happy to consult for your specific needs!