Largely dependent on what you mean by "business man", but going from dev to sales can be as easy as transitioning to a sales engineering / solutions architect role and getting exposure to closing deals that way. The next leap you'd make is figuring out how to get into a closing role; which will take a little patience in order to find a good fit (namely: a company willing to put someone with engineering experience in a closing role -- they're out there!).

If you mean other parts of the business (operations, finance, BD, etc), the pattern is probably similar -- find a technical role that's in that org and start there, with the intention of moving into the business side more and more.

If you mean "I'm a software developer and want to understand the business side of running a company better", there is a ton of reading you can do to learn how businesses work. Some books that were helpful to me:

  * The 4 Steps to Epiphany by Steve Blank
  * How to Win Friends and Influence People by Dale Carnegie 
  * The Personal MBA by Josh Kaufman
  * The E-Myth Revisited by Michael Gerber
  * Venture Deals by Brad Feld

Ultimately business skills are gained the same way you'd learn software skills -- self-study combined with exposure to the problems you're interested in solving.

One place you can start that is not so far away is making a transition from code to the product. The good news is you don’t really need anyone’s permission to do this since you are close to the product already.

A lot of developers focus on the “what” and “how” because that is the bulk of their job. Start looking at the “why”. Start asking questions when you don’t understand the “why” - being careful to present yourself as curious rather than sceptical. Try to understand the motivations behind decisions, and the trade offs that are often required.

As you become a master of the product - again not just what you’re building but why - you’ll likely find yourself with opportunities to contribute much more in the business side.

I went the other way - I was a business grad and transitioned to a software developer. IMO the soft skills are important no matter what. To be a real thought leader in business it's important to step away from the work and trying to think about the problems you're facing (people problems for example) in lateral ways. A lot of very technical people have a hard time stepping away from the work IMO. You just need to trust people to do the best work that they can. There is a great quote from Steve Jobs: "It doesn't make sense to hire smart people and tell them what to do. You hire smart people and let them tell you what to do."

I had a college degree in business, but as a contractor I started saying yes to more work than I could handle myself which forced me to hire contractors.

As others mentioned, you have to stop writing as much code and start QAing or PMing more which takes practice.

But the short answer is, don't turn down work and be prepared to work a ton while you're still part time coding and part time managing.

It is hard. I still struggle with this myself. The first thing you have to do is stop writing code. You have to get comfortable letting someone else handle that side of it.

You have to learn to focus more on sales, marketing, and growing the company... not little details about the code.

I moved into testing and requirements gathering, learned as much as I could about project management and ultimately got an MBA.

Volunteered to help my company bid on projects and run them.