Human Luck is one of the factors which can help to improve your Heaven Luck and even Earth Luck.
ie. Say you are a weak person and your life is always following your inauspicious path.
Does it mean that you will be bound to have very inauspicious life?
No. This is because you can actually borrow someone else luck to boost your own luck.
In Feng Shui your Children is your greatest Wealth. Many times people nowadays always relates Wealth to physical money.
However, in Feng Shui it is your Children which represents wealth.
Why? Simply, if you educate and bring up your children, they will in turn look after you when you are old. So, say if you bring up 3 very filial children. One is a doctor, another is a Lawyer, another is a businessman. When you are old, you have them to depend on and they will allow you to leave a comfortable life.
Compare it with another person who does not have children but just have physical money. A person can only work upto a certain age say 60. And all his savings depends on how much he has saved during his working days. Say he has saved $100,000. Will that amount be able to sustain him for a long period of time during this old age?
So, you see in Feng Shui Human Luck which can be related to many areas such as family relationship particularly your children. Thus, your children's individual luck can be taken advantage of so as to boost your own Heaven Luck.

Related: Understand what is Human or man luck?