My lessons learned running a 100KM ultra marathon

Adriaan Kolff
5 min readAug 2, 2022

Can you imagine running 100KM non stop through the mountains?

If you would have asked me two years ago I would have told you “no way, you are crazy”.

Now, two years later, I did just that.

I ran a 100KM ultra marathon in the mountains of Oregon with over 3.400 meters of elevation (12.000 feet). It took me 13 hours and 42 minutes to complete.

These are my learnings of going from ‘no way, you are crazy’ to training and running a 100KM ultra marathon.

My happy face after finishing the race


Every year I try to commit to one race. The race date holds me accountable. It makes me run in the rain, heat, storm and snow. It provides me with structure as I need to plan my days and weeks around my training schedule.

If you have difficulty keeping a fixed training schedule for yourself? Sign up for a race and let your friends know. Or even better. Find someone to run the race with and hold each other accountable.

I worked with a coach

This was the first year I worked with a running coach, Wilfred van Holst.

I started my training five months prior to the start of the race. I trained on average between 6 to 12 hours per week.

Every week my coach would send me my training schedule for the week ahead.

The furthest I ran was 32KM. The longest I ran was 3 hours. Almost every training was interval based.

This made my trainings very efficient and minimized the risk of injury.

From now on I will always work with a coach.

This goes for everything that you do.

Starting a company for the first time? Have a seasoned entrepreneur as an advisor.

Your first child? Talk to other parents and learn from them.

Stressed out? Talk to a therapist.

Don’t try to figure things out yourself. Ask someone that is an expert in his or her field.


When you go to war. You prepare for battle. I did the same for my race. I prepared for battle.



Adriaan Kolff

Co-founder of MatcHR, investor, entrepreneur. I write about entrepreneurship, recruitment & productivity. Follow me here or on LinkedIn.