Why do we place such emphasis on "what we do." God looks at our heart, motive first and foremost.
As for rewards, well I'm sure I won't have any but I'm not going to worry about it because all I want is to spend eternity with our sovereign Creator, God Almighty, maker of Heaven and Earth.
And as for "what we do" are we to go around trying to prove our salvation to others? Not me. It is God I am concerned with and that He knows my heart/soul and that He has done all the work for my salvation and sealed it with the seal of the Holy Spirit.
You are right, "what we do" is just who we are, not much then.
Nothing we do comes from anything but that which is in our hearts.
It is like saying warmth of a heating system exists but what is important
is the flames that make the heat. Well we have the flames to create the
warmth, you cannot have one without the other.
If one claimed one had the flames but there was no heat, it is obvious this
is not true. So when a heating system which should be working is cold, you
know the flames have gone out.
Now unfortunately we are not God, we cannot see peoples hearts but we can
see what they do. So if people are being treated well, blessed, uplifted and
encouraged in good things and praising the Lord, it is reasonable to assume
the heart is good.
This is so simple Jesus said this
No good tree bears bad fruit, nor does a bad tree bear good fruit.
Each tree is recognized by its own fruit. People do not pick figs from thornbushes, or grapes from briers.
The good man brings good things out of the good stored up in his heart, and the evil man brings evil things out of the evil stored up in his heart. For out of the overflow of his heart his mouth speaks.
Luke 6:43-45
By their fruit you will recognize them. Do people pick grapes from thornbushes, or figs from thistles?
Likewise every good tree bears good fruit, but a bad tree bears bad fruit.
Matthew 7:16-17
The ax is already at the root of the trees, and every tree that does not produce good fruit will be cut down and thrown into the fire.
Matthew 3:10
Likewise every good tree bears good fruit, but a bad tree bears bad fruit.
A good tree cannot bear bad fruit, and a bad tree cannot bear good fruit.
Every tree that does not bear good fruit is cut down and thrown into the fire.
Matthew 7:17-19
Make a tree good and its fruit will be good, or make a tree bad and its fruit will be bad, for a tree is recognized by its fruit.
Matthew 12:33