'Faint hearted' in the Bible

and in the doing good we may not be faint-hearted, for at the proper time we shall reap -- not desponding;

But we exhort you, brethren, admonish the disorderly, comfort the faint-hearted, sustain the weak, be patient towards all.

Therefore, if you would escape becoming weary and faint-hearted, compare your own sufferings with those of Him who endured such hostility directed against Him by sinners.