Summary: We add several things to our life, but how about adding the one thing we need the most. Faith. .
2 Peter 1:5-10 KJV
 And beside this, giving all diligence, add to your faith virtue; and to virtue knowledge;
 And to knowledge temperance; and to temperance patience; and to patience godliness;
 And to godliness brotherly kindness; and to brotherly kindness charity.
 For if these things be in you, and abound, they make you that ye shall neither be barren nor unfruitful in the knowledge of our Lord Jesus Christ.
 But he that lacketh these things is blind, and cannot see afar off, and hath forgotten that he was purged from his old sins.
 Wherefore the rather, brethren, give diligence to make your calling and election sure: for if ye do these things, ye shall never fall:
"For if these things be in you, (What things: Faith, Virtue, Knowledge, Temperance, Patience, Godliness, Kindness, and Love, they make you that you shall neither be barren nor unfruitful. But he that lacks these things is blind, and cannot see afar off, and has forgotten that he was purged from his old sins.
This easily leads me to believe that these several things work together, and if any of them are missing, we are considered as blind. Verse 8 tells us if we have these things, then we shall not be:
1. Not producing fruit; barren; as an unfruitful tree.
2. Not producing off-spring; not prolific; barren; as an unfruitful female.
3. Not producing good effects or works; as an unfruitful life.
4. Unproductive; not fertile; as an unfruitful soil.
Tying this in with the fruit verses in Galatians, there is a way for us to bear fruit, adding one thing to another and possessing and abounding in the combination of these things.
(22) But the fruit of the Spirit is love, joy, peace, longsuffering, gentleness, goodness, faith,
(23) Meekness, temperance: against such there is no law.
Galatians 5:22-23 Amplified
(22)But the fruit of the [Holy] Spirit [the work which His presence within accomplishes] is love, joy (gladness), peace, patience (an even temper, forbearance), kindness, goodness (benevolence), faithfulness.
(23) Gentleness (meekness, humility), self control (self-restraint, continence). Against such things there is no law [that can bring a charge against you].
Genesis 2:9 KJV
And out of the ground made the LORD God to grow every tree that is pleasant to the sight, and good for food; the tree of life also in the midst of the garden, and the tree of knowledge of good and evil.
Now there is a direct correlation between the fruit of the spirit and the works of the flesh and the tree of life and the tree of the knowledge of good and evil. I am not over spiritualizing. It is in the BOOK.
Jesus said: Matthew 7:16-18 KJV
 Ye shall know them by their fruits. Do men gather grapes of thorns, or figs of thistles?
 Even so every good tree bringeth forth good fruit; but a corrupt tree bringeth forth evil fruit.
 A good tree cannot bring forth evil fruit, neither can a corrupt tree bring forth good fruit.
In the mathematics of heaven, in order to be fruitful we must do some heavenly addition: