Jesus taught about it in Mark 4:26-29.
There, He said:

So is the kingdom of God, as if
a man should cast seed into the
ground; and should sleep, and
rise night and day, and the seed
should spring and grow up, he
knoweth not how. For the earth
bringeth forth fruit of herself;
first the blade, then the ear,
after that the full corn in the ear.
But when the fruit is brought
forth, immediately he putteth in
the sickle, because the harvest
is come.

According to the law of sowing and
reaping, if you want health, you need
to do more than just want it. You need
to do even more than believe in healing.
You need to plant seed that will
eventually grow up and yield a harvest
of health.

What kind of seed produces physical
health? Proverbs 4:20-22 tells us:
“My son, attend to my words; incline
thine ear unto my sayings. Let them
not depart from thine eyes; keep them
in the midst of thine heart. For they
are life unto those that find them, and
health to all their flesh.”

That word health in Hebrew means
“medicine.” God’s Word has life in it.
It is actually spirit food. As you feed
on it, you become strong spiritually
and physically.

“Let them not depart from thine
eyes.” Read the Word. Meditate on the
Word. That’s taking God’s medicine.
If you will be faithful to take it continually,
it eventually will be as hard
for you to get sick as it ever was for you
to get well.

But it’s a process. You can’t just read
the healing scriptures once and then
go on about your business. You must
continually feed on the Word of God to
keep the crop of healing coming up in
your life.

Kenneth Copeland Ministries