If you want the immune system of a 20-year-old when you’re older, doing lots of exercise now and sticking with it could get you there.

Researchers in the United Kingdom have discovered that older lifelong endurance cyclists had immune systems similar to young adults.

So, if you’re in your 20s or 30s, now’s a good time to get started. But even if you’re older, it’s never too late to increase your physical activity.

If you tuned out earlier when you read “lots of exercise,” don’t click away just yet.

By starting small and building gradually, you can work up to a solid exercise plan in just a few months.

We’ll give you some tips on just how to do that.

But first, the new study.

Researchers recruited 125 long-distance cyclists between 55 and 79 years old.

These weren’t just easy riders.

In order to be included in the study, men had to be able to cycle 62 miles in under 6.5 hours. Women had to cycle 37 miles in less than 5.5 hours.

Researchers found that the older cyclists produced similar levels of T cells as young adults, whereas inactive older adults had much lower levels.

T cells help the immune system respond to new infections. They are made in the thymus, a gland in the chest that shrinks and produces fewer T cells with age.

The immune system starts to decline in early adulthood. This is why older people are more susceptible to infections, inflammatory diseases, and autoimmune diseases such as rheumatoid arthritis.

The study was published March 8 in the journal Aging Cell.

The researchers focused on endurance cyclists, partially because they keep good records of their physical activity.

But Janet Lord, study author and director of the Institute of Inflammation and Ageing at the University of Birmingham in England, told Healthline that she suspects other endurance activities, such as running, would offer similar health benefits.

She also suspects that lower levels of exercise might provide some benefit.

“Within our group of cyclists, they all got the benefit no matter how far they cycled each week,” said Lord, “though most were doing 100 kilometers or more.”

Setting your sights

More research is needed to answer questions such as what’s the optimum amount of exercise to boost your immune system, and can you regain a youthful immune system if you start exercising late in life?

But lots of research already shows that exercise is good for your health, so why wait any longer to get started.

Here are a few long-distance activities to choose from, along with distances that you should be able to cover within 6.5 hours.

  • Cycling: 62 miles
  • Cross-country skiing: 26 miles
  • Flatwater canoeing or kayaking: 20 miles
  • Hiking: 15 miles
  • Running: 26 miles

Of course, how fast you go depends on many factors such as hills, the gear you carry, weather, and how many times you stop to take a “selfie.”

Covering this distance in 6.5 hours, though, is not a super-fast pace. Still, going this far can be challenging if you’re just getting started.

That’s why it’s important to start at a level — distance, duration, and intensity — that you are comfortable with.

Shayla Roberts, a certified personal trainer and coach based in Canada, also recommends that you not jump ahead too quickly.

“Increasing the intensity, the duration, or the distance in your training rides no more than 10 percent each week allows for all body systems to develop and get stronger while allowing you to recover properly,” Roberts told Healthline.

Starting small will also help you develop the habit of exercise, which may be even more important than how much distance you cover.

“Many people quit cycling or exercising because they do too much too soon,” said Roberts.

Training plans to get you started

Roberts shared two workouts for beginners wanting to eventually go the distance.

You can scale these back if you need to. And you should check with your doctor before starting any new exercise program.

Cycling

  • Monday 45-minute interval ride:
    • 10-minute warm-up
    • Intervals: Alternate 5 minutes at 80 percent of your maximum effort, and 2.5 minutes at an easy pace. Repeat four times.
    • 5-minute cool-down
  • Wednesday 60-minute ride, steady pace
  • Friday Easy 30-minute ride
  • Saturday Long ride: Start with 90 minutes. Add 15 to 30 minutes each week until you reach your desired time or distance.

Cross-Country Skiing

  • Monday Easy 45-minute ski
  • Wednesday 35-minute interval ski:
    • 10 min warm-up
    • Intervals: Alternate 1 minute fast and 1 minute easy. Repeat 10 times.
    • 5-minute cool down
  • Friday 30-minute ski, steady pace
  • Saturday Endurance ski: start with one hour. Increase duration 10 percent each week until you reach your desired time or distance.

You can use a similar plan for other long-distance activities. You can even do some or all of your cycling in an indoor spin class.

Marathon running, though, needs a more focused plan because running can be harder on your body than cycling.

Meghan Kennihan, a personal trainer, run coach, and cycling coach based in Illinois, told Healthline that beginners should plan to spend 12 weeks building up to a half marathon.

From there, it will take another 16 weeks to build up to a full marathon — for 28 weeks total.

Kennihan also has a half-marathon training plan that includes details on things such as the intensity of each run, alternating fast and slow intervals, sprints, and core workouts.

She also recommends that you do more than just aerobic exercise.

“You still need to weight train and do some plyometric exercises for your bone health, especially for those who are over 30,” said Kennihan.

If long-distance activities aren’t your thing, find something that you enjoy doing — that’s what you’re most likely to stick with as you get older.

This will make all the difference.

Because while it’s amazing that an 80-year-old can cycle 62 miles, what’s even more impressive is that they’ve been riding consistently for sixty-plus years.