If this answer is allowed, the best answer is that you would need to give the person some education. An uneducated person is most in need of education in order to be more economically productive to society. This would not necessarily have to be academic education. It could also be something like vocational training. However, it would have to be something that would make the person more productive. Education or training is the best way to accomplish this.
Please note that this applies only to economic productivity. An uneducated person is no less likely to be productive in other ways than an educated person.
I was even further into the subject matter considering people living at and below the "poverty" level in America. Having lived in and around the homeless as I am currently homeless as well, society tends to shun the poor and seems to want to punish them for just trying to survive in a rather cruel environment. I am homeless by choice as compared to many that are homeless by circumstances.
What you don't recognize in these people is talent and knowledge that is hidden
and who are afraid to show it because they feel it is not important to anyone else. The struggling minority need help just as the rich who get breaks and maneuver through loop-holes.
Perhaps I was looking for a "motive" to measure a persons ability to comply with whatever incentive.