I worked in Management Consulting for 4.5 years.

In that time, I collected some amazing experiences:

• Evaluated which real-estate an energy company should keep in its portfolio - and which to get rid of

• Helped test an actuarial system for a big insurance company

• Improved an Excel model that suggested which IT assets should be replaced when

• Ate 27 waffles with whipped cream and nutella while meeting consultants from all over the world in our company training center near Chicago

There isn't much I would change about my journey.

But if I could go back, here are a few of the mistakes I made in my first years—and what I would have done differently:

Mistake 1: Not saying "I don't know how to do this" early enough

Everyone around me seemed so busy. Even when I was struggling with something, I would not dare to ask for help.

Trying to figure stuff out on my own resulted in a lot of stress - and poor performance.

Today: If I was asked to do something, but would not be clear on how to do it - I would ask immediately. I would not stop asking until I would get a clear guidance how to get it done.

Mistake 2: Volunteering Mindlessly

It's good to be the "nice guy" helping everyone out. But without giving it any thought, I often ended up doing stuff that was hard to do, but nobody appreciated.

Today: I would offer help with things that were hard for the other person to do - but easy for me. And I would make sure I get the credit!

Mistake 3: Focusing more on "Doing Pretty Slides" than "Understanding the Business"

Our deliverables were the slides. It was my job to create the slides. And trust me, they had to be very pretty slides.

I ended up spending 80% of my time on making the slides pretty and only 20% of time on trying to understand what was the big idea on those slides.

Today: I would drastically cut the time on making the slides pretty. Instead, I would think more deeply about the work I was doing. And I would also get more sleep.