Jn 3:16 God so loved the world that He gave His only begotten Son, that whoever believes in Him should not perish 622  but might have everlasting life
[subjunctive cf 1:12]

I. The Gift of Eternal life

is not existing forever, for we already do this, nor justification/forgiveness by faith, because it can be lost
Eternal (adj of aion=age) sometimes means lasting forever, but frequently means “of The Age” especially when coupled with “life”
“Life” is not mere breathing, but most often means Dominion when used in contexts addressed to believers. One determines what meaning the author intended by observing the context, audience, actions advocated, reasons and motivations, thus entering into the author's thought.

Rm 2:5..righteous judgment of God, 6 who "will payback to each one according to his deeds: eternal life to those who by patient continuance in doing good seek for glory, honor, and incorruption; 8 but to those who are self-seeking and do not obey the truth, but trust unrighteousness - indignation and wrath, 9 tribulation and anguish, on every soul of man who does evil... 10 but glory, honor, and peace to everyone who works what is good 13...the doers of the law will be justified; 16 in the day when God will judge...acc to my gospel. (see Getting & Maintaining EL last wk)

Wrath/loss Eph 5:1 be imitators of God as dear children 2  walk in love...3 But fornication and all uncleanness or covetousness, let it not even be named among you...fitting for saints...5 know that no fornicator, unclean person, nor covetous man, who is an idolater, has any inheritance in the kingdom of Christ and God. 6 Let no one deceive you with empty words, for because of these things the wrath of God comes upon the sons of disobedience. 7 Therefore do not be partakers with them. 8 once darkness...Walk as children of light Rev 2:22 11:18; 14:9-15

II. Eternal Life is equated with inheritance/reward

that can be forfeited, maintained or enhanced by works. 1Cor 3:15; 9:27; 10:1-13; 2Pt 1; 2Jm 8
Col 3:24 since you know that you will receive an inheritance from the Lord as a reward. It is the Lord Christ you are serving  cf Mt 7:19-27

Heb 6:12 We do not want you to become lazy, but to imitate those who through faith and patience inherit what has been promised.
Faith is not mere assent to information, but confidence/trust in the revealed promises of God  (expressed in action -Heb 11:6) Isa 40:10

III. Neither the Kingdom of Heaven(s), nor the Kingdom of God is heaven

but is the future Messianic Age/Kingdom promised in OT/NT
Sermon on the Mount Mt 6:33  seek first the kingdom of God and His righteousness, and all these things shall be added to you. 

Mt 19:16 what good thing must I do to get eternal life?" 17 If you want to enter life, obey the commandments 18 "Which ones?" Jesus replied: Do not murder/commit adultery/steal/lie 19 honor your father and mother, and love your neighbor as yourself.  20 "All these I have kept, What do I still lack?" 21  If you want to be perfect, go, sell your possessions and give to the poor, and you will have treasure in heaven. Then come, follow me.

B2. Question: v16  do to get ? B2a. What does he have to do? 17 If you want to enter life, obey 21 sell and give, then follow (as a disciple)
B2b. What does he get? 17 If you want to enter life; 21a be perfect; 21b treasure in heaven; 23-214 enter the kingdom of heaven/God 25 saved
See Study Guide to Rewards on Truthbase.net

Diligently seeking God is a wholehearted pursuit of obedience resulting in a transformed mind and life and enhanced eternal reward.
2Pt 1:3 called us by glory and virtue. Having escaped corruption...that is thru desire. 5 giving all diligence, add to your faith virtue/knowledge, 6 self-control/perseverance/godliness, 7 brotherly kindness,/love. 8 For if these things are yours and abound, you will be neither barren nor unfruitful (cf Mk 4:19; Jn 15) in the knowledge of our Lord Jesus Christ. 9 For he who lacks these things is shortsighted, even to blindness, and has forgotten that he was cleansed from his old sins. 10 Therefore, brethren, be even more diligent to make your call and election sure, for if you do these things you will never stumble; 11 for so an entrance will be supplied to you abundantly into the everlasting kingdom of our Lord

Flesh=temporal desire for power (security, significance), pleasure/comfort, and possessions. [cf cares of this world...desire for other things -Mk 4:19]
Rms 8:3 He judged sin in the flesh 4 that the righteous requirement of the law might be fulfilled in us who do not walk acc to the flesh but acc to the Spirit. 5 For those who live acc to the flesh set their minds on the things of the flesh, but those who live acc to the Spirit, the things of the Spirit. 6 For to be carnally minded is death, but to be spiritually minded is life and peace Gal 5:16-21 (no inheritance), 24

Questions for Reflection/Discussion/Response:

1. Who was the audience of Jesus? How were OT Jews saved?  Who were the recipients of the NT writings? (belief in Day of Atonement)
2. Does God judge His people//believers Heb 10:30? What's  th judgment for those undiligent “justified” who are unfaithful/carnal/disobedient? 2Cor 5
3. Are those who love Jesus loyal. obedient and fruitful Jn 14:15; 15:5,10?  How would you rate your fruitfulness and future prospects in the Kingdom?
4. What drives/motivates you? What are your desires/lust? Are you following Jesus in obedience acc the HS, or the following your/Satan's will?
5. Do you have a barren faith or will you reap the reward of an abundant inheritance in the kingdom? What makes the difference?