The English term used for a complete and happy person

Solution 1:

How about stand-up guy (or politically-correct equivalent for guy)?

From M-W dictionary:

stand-up: marked by a high degree of personal integrity of loyalty, e.g., a stand-up guy

From M-W thesaurus:

stand-up: following the accepted rules of moral conduct, e.g., he's a real stand-up guy, he's willing to raise the child—by himself if necessary

Synonyms for stand-up: decent, ethical, honest, honorable, just, noble, principled, respectable, righteous, upright, upstanding

Your examples:

How can we guide my son to become a stand-up guy?

Despite his struggles in life, he was a real stand-up guy.