About Us

We Save Your Time

We don’t just talk about it – we get it done!
Hands-on, no fluff, results-focussed!

〉No matter if you need a team or automatisms, we work with people AND technology, but make it understandable and convenient for you.

〉We don’t accept mediocriticy but find the best solution for your specific needs.

〉We will even deal with vendors so you don’t have to.

〉We see business in its entirety and make sure that everything works together so that your business functions as a whole and works for you!

You are best at what you do – we cover everything else for you.


Work On Your Business was founded by Mona Tenjo and Hajo Sonntag to help business owners, self-employed freelancers and entrepreneurs to work ON their business instead of IN it.

“It is our goal is to help entrepreneurs build sustainable and profitable businesses that support the desired lifestyle of our clients!” – Hajo S.

Find Out What We Can Do For You or
Contact Us To Discuss Your Specific Needs!

Our Mission & Values

It is our mission to help entrepreneurs work ON their business, not IN it. We help our clients to regain their freedom, keep their focus on the right topics and thrive in business.

Our core values are RESPECT, EXCELLENCE and RELIABILITY. We stand for: Do it once – Have it forever! And adjust when necessary. Because you don’t pay for the time invested, you pay for results! And that’s what we deliver: RESULTS!


Respect is our number one value in everything we do. We respect your time, we will treat your business and your expenses as if it was ours and always meet as equals.


We don’t accept mediocrity. As engineers and strategic consultants, we always strive for building sustainable, functioning solutions that are tested and meeting client’s needs. Our clients deserve nothing but the best – and we will go the extra mile to make that happen.


As original Germans, we love solid foundations and we take words literally. Our word is our bond. We won’t leave you standing in the rain when obstacles come along. We stick with you and work it out. You can count on us!

Meet The Founders

Mona Tenjo

Mona gathered more than 15 years of experience in the areas of accounting, purchasing, business management, project management and even pre-sales. Her strong work-ethics allowed her to climb the career ladder and gain insights on various levels within companies of different sizes.

Mona’s strong track record led her to consult some of the largest organizations, such as Siemens, DP DHL, and HeidelbergCement, and lead the implementation of complex global projects.

Her degree in International Business was extended by countless client projects over the years, that equipped Mona with a profound knowledge of how to make the best out of any business, how to add value to any organization or endeavour, and how to create championship teams. She accomplished to train experts of more than 45 different nationalities in over 15 countries around the world, from half of Europe to Indonesia, Russia, Tanzania, USA and others.

Hajo Sonntag

Hajo honed his skills in the technical world of engineering, research and development, and project management at automotive giants like Volkswagen, BMW, Faraday Future and even Fraunhofer Institute.

His technical hands-on education and Master of Engineering degree trained his natural talent of troubleshooting the origins of problems and developing solutions to solve them once and for all.

Being responsible to manage large projects such as developing and launching an entire car and coordinating thousands of people across the globe to work together to achieve a common goal, sharpened his focus on the overall picture for project and company, as well as providing an immense knowledge-base of technical and business strategies and know-how to being able to solve any problem. Additionally, his martial arts career formed and strengthened his character, taught him discipline, leadership, and the value of strategic foresight.

Today, he finds himself as technical and business consultant, partner in media and jewelry businesses, and even mentor.

Get Started Today

If you want to discuss a specific issue that you face or evaluate your development potential, get in touch with us.

Let’s talk