Finding the right people with a high level of commitment after the excitement of a new idea has worn off.
Finding the best people in the world and getting them to work together as a functional team.
The biggest challenge was to know and understand the market. Some applications and programs seemed good to the developers and promoters but customers may not use it as expected.
On the personal side it's the creative mindset: how to find new selling techniques, growth hacks and unique emotional contents to differentiate the company from others in the customers' perspective.
However in my opinion, tasks are hard if they don't fit our own skills and type of entrepreneurial profile. An extrovert will find it hard to analyse data constantly while an introvert can struggle building a team. A creative mind will have a hard time focusing on financial analysis and planning while a trader will find it hard to communicate his vision to the world.
Rather than doing everything by ourselves I think it's important to know our own strengths/weaknesses, find (a) complementary co-founder(s) to deleguate our "biggest challenges" and focus on using our skills to accomplish the tasks we master and enjoy. Prsonal opinion and happy to read your thoughts.
Huge difficulty raising capital
to make a meaningful team .
Getting your first customer, especially on service industry, that has been a really big challenge