Here’s a startling fact that I’m confronted with every day: Cardiovascular disease is the number one cause of death for men and women in this country, and up to 80 percent of it is preventable. The amount of exercise we get as a society is really low—a fact that has motivated me to exercise more regularly, and has definitely been on my mind as I’ve been training for my third marathon.

I’ve run one marathon a decade for the last three decades. My first one was in 1997, when I was in my 20s and in medical school. Before then, I wasn’t a particularly avid runner (to be honest, running 26.2 miles felt insurmountable when I signed up), but I was diligent about my training and race day was one of the best days of my life. My second came in my 30s, when the training was slightly more challenging since I had limited time as a doctor with two kids, and it was a lot harder than my first. Now, in my 40s, I’m getting ready to do it again in honor of Christy Turlington Burn’s foundation, Every Mother Counts, which raises awareness and funding for maternal mortality—a cause that’s very important to me as a cardiologist who specializes in the care of women with heart disease in the peripartum.

I definitely do feel like I’m a bit older—I have more aches and pains, and my legs feel more sore after an 18-mile run than they ever did when I was younger. But this time, I’ve decided to really train because I want to do it the right way and try to feel closer to how I felt when I was 24. So, I’ve decided to follow the conservative 16-week plan from New York Road Runners. I run five days a week, and most of the weekday runs are in the three to six mile range. Each week, there’s a long run (which I usually do on Sundays), and this increases as your training progresses. The first week I ran six miles, then eight, then 10, all the way up to 20. About four weeks ahead of the marathon, I’ll taper back down. You never actually run 26 miles until the day of the race, because the idea is that if you’re in good enough cardiovascular shape to run 20 miles, you can make it through a marathon. I’d guess that I run anywhere from 25 to 35 miles a week during training.

I’ve always had a healthy diet, and my eating hasn’t changed that much during training. Before runs, I tend to do a little bit more carb loading, but I’ve always followed a Mediterranean-style diet with fish, chicken, vegetables, pork chops, fruit, and that stays pretty much the same. I’ll have a few glasses of wine during the week throughout training, but I plan to cut alcohol out entirely four weeks leading up to the race.

As far as motivating goes, it isn’t always easy. Sometimes, I’ll admit, I get home from work, and I just do not feel like running eight miles, or whatever that day’s distance is. Then I remember that it’s only a few more weeks of training, and think about that meme that’s all over the Internet that says: “‘I really regret that run,’ said no one ever.” It really is true—once every training run is over, I’m so, so glad I did it.

I certainly don’t want people to think that they have to run a marathon to be a good cardiovascular shape. But training has reminded me about what a difference it makes to do 30 to 40 minutes a day of cardio a few days a week. You feel better, you sleep better, you have more energy. It also keeps your mood up and anxiety levels down, which is great considering how stressed most people are these days. As a cardiologist, especially because I’m 46, I’ve been thinking about how I want to be in good cardiovascular shape as I get older. I’m fully aware of the fact that since I’ve started training this time around, my resting heart rate is much, much lower.

Marathons are great in the sense that they motivate you and give you a goal that you can feel proud of, but excessive running may not be so great for everyone. And actually, you can get some of the same heart-health benefits by committing to doing 45 minutes of cardio every week. We know that if your heart rate is at your maximum predicted heart rate for those 45 minutes on a regular basis, it has huge benefits. It improves your exercise capacity and your heart function, prevents coronary artery disease, and lowers blood pressure and cholesterol. Running the marathon, for me, is great—but it doesn’t have to be a must-do for anyone prioritizing their heart health.

That said, anyone can do it (barring any physical or medical complications), but it comes down to the training. No matter where you’re starting from, it’s best to build up slowly. If you’re in good running shape already, you can jump right into a training plan, but even if you’ve never run a mile before, it’s definitely still possible—just be sure to choose a longer-lead training plan that will give you 20 weeks (or more) to prep your body. No matter how long your training is, it’s about building fitness and endurance until you’re ready to lace up for 26.2 on race day.

As told to Zoe Weiner on September 26, 2019.

Getting ready to run the marathon yourself? In addition to hitting you mile marks, be sure to stretch and work your core, too.