How to make someone help you willingly?

"I am busy right now", he used to reply every time I ask for his help in my projects. Well, I am stuck by myself again! Days gone by and I began thinking I don't have the ability to persuade anyone, until I realize a simple  lesson of life, 

Source

If you want someone to help you willingly. Let them feel like they are gaining something from it.

Now, that I stated it might seem pretty obvious. But sometimes, the obvious is never so easily attained. Nobody ever takes effort for someone, if he/she is not gaining something from it. Even the big companies like Facebook and Google claim to provide services for free, but in return they are also getting your behavioral data, which in turn is being cashed through their robust algorithms through adverts. Its just that they are aiming for something else that you don't care about. Someone may be gaining reputation, someone would rather aim for expanding their business, or some people may be looking for experience. Not every gain can be measured in terms of money. 

Knowing the other party's needs, comfort zone, etc. may be a good start. Try putting yourself in their shoes to understand them better. Be prepared as to what the other person might gain from collaborating with you or helping you out. This may give you upper hand while asking for help or while pitching some idea and you can persuade them readily. Let them understand why they shouldn't go for something else. Don't hold them back, rather help them flourish and progress. Try to find a way to create a WIN-WIN situation. 

The gain that he is seeking need not be always some kind of a reward, rather try to figure out some genuine gains that can be attained. Through sincerity, make him believe you. This way, the chances of you persuading is almost certain.  

Some Related Posts:

Five Ways to Get Anyone to do Anything you want - Bruce Kasanoff

How to get people to say Yes to what you want, according to science - Christina DesMarais