Mistakes to avoid when going from 10 km to a half marathon

You've already run several 10Ks and feel ready to take it to the next level with a half marathon ? Congratulations! The half marathon is an exciting challenge ... but beware of the pitfalls that await beginner runners. Between training too intensely, poor hydration management, and even the wrong choice of shoes (yes, running 21.1 km in worn-out sneakers is a very bad idea), there are mistakes to avoid. Here's a complete guide to approach this transition smoothly, or at least, without too much pain.

Why the transition from 10K to half marathon is a unique challenge

Running a 10K is intense, fast, and explosive. A half marathon, on the other hand, requires a more strategic approach. Effort management becomes paramount: you must learn to run long distances, fuel well along the way, and listen to your body. This isn't just a "double dose" of 10K... otherwise, we'd call it a "double 10K" and not a half marathon !

Common mistakes to avoid when transitioning to a half marathon

Mistake #1: Increasing distance too quickly

We know the desire to progress quickly is strong. But trying to go from 10 km to 21 km in a few weeks is like trying to build a house in a weekend: it's going to collapse.

What to do :
• Gradually add kilometers to your long run (1 to 2 km more each week).
• Don’t neglect recovery: more effort = more fatigue.
• Listen to your body and accept the days when your legs say “no” (sometimes they are right!).

Our unique recovery shower gel, specially developed to aid your recovery, will be a valuable ally for your first marathon and throughout your running life.

Mistake #2: Neglecting nutrition and hydration for the half marathon

For a 10km race, you can afford to skip the refreshment stop. For a half-marathon, it's a different story: if you don't eat, you risk hitting the dreaded invisible wall (the one where your legs turn into reinforced concrete).

What to do :
• Test your training nutrition: a good energy drink and electrolytes if it's a bit hot are essential
• Hydrate yourself regularly: don’t wait until you’re thirsty, it will be too late.
• Don't change your strategy on race day: this is not the time to experiment with the exotic papaya-mint drink.

Mistake #3: Forgetting mental preparation for the half marathon

A half marathon is also a mental battle. In a 10K, you're pushed hard from the start. In a half marathon, you have to manage your effort and hold your ground mentally.

What to do :
• Mentally divide the route: don’t think “21.1 km”, but “three blocks of 7 km” for example.
• Have a motivating mantra: “One step at a time”, “I am stronger than the distance”, or even “I paid my registration, I will finish it!”
• Imagine yourself crossing the finish line: it boosts you more than you think!

Tip: Blackbelt provides you with its best experts; think about our coach to have the best mental preparation.

Mistake #4: Running with equipment that isn’t suitable for a half marathon

If your running shoes are from your first 10K, it might be time to say goodbye (or at least reserve them for Sunday strolls). The wrong pair can turn your half marathon into a blister-filled, sore nightmare.

What to do :
• Choose suitable shoes: try them on several long runs before the race.
• Dress appropriately for the weather: sweating under a windbreaker in the sun is not the most pleasant experience.
• Never try on new things on the day: The brand new t-shirt may look great… until it irritates your skin for 21 km.

We hope this helps you avoid mistakes as you transition from 10K to a half marathon.

Mistake #5: Think about your joints!

It's a real challenge for your body! Ideally, you should strengthen your joints with a complex designed for a month-long treatment before the big day. Knee pain, for example, can prevent you from completing your workout.

Practical tips for a successful transition

Plan and follow a progressive program

A good training plan should include:
✅ One long outing per week, gradually increasing in distance.
✅ Interval sessions to improve your endurance.
✅ Rest days, because sleep and recovery are part of training.

Test and adjust your nutrition during long rides

Don't set off on a half-marathon empty-handed. Take advantage of your training sessions to test your supplies and avoid unpleasant surprises.

Mentally prepare and manage stress

If you start to feel stressed as the race approaches, that's normal! Put it into perspective: it's a race, not a math test.

Testimonies and Anecdotes: Laughter and Lessons Learned Along the Way

Every half-marathon runner has a rookie story to tell. From the one who forgot to tie their shoelaces to the one who took a gel without water (a fatal mistake), everyone makes mistakes. The important thing is to learn and improve!

You also have the right not to seek performance, and to do a half-marathon for fun , our article on the subject will surely interest you if this is your case.

And if you want more advice on preparing for your first marathon, here is another useful article.

Conclusion for going from a 10km to a half marathon

Going from 10 km to a half marathon is a wonderful adventure that requires preparation and patience. Making common mistakes maximizes your chances of arriving fresh (or almost) at the finish line. So train, prepare your mind, and take on this challenge with a smile (and the right shoes)!