This is a long title, but it really is something to ponder as a Christian because often, we are not living with conscious awareness of the eternal consequences of their choices and actions. Eternity is real, it is you ruling with Jesus Christ forever and ever over all of Creation, and everything you have, your destiny itself, is set on the basis of everything you did in your temporal existence on planet earth. The key thing is being faithful to and honoring God whether we are enjoying the heights of success and riches or enduring the depths of failure and poverty.
Enduring in faithfulness and submission to God, honoring God with our words and deeds, empowered by the Holy Spirit transforming us, we build our eternal destiny and accrue rewards, and yet we earn nothing. We please God because we allow the Word and the Spirit to dwell in us and transform us into what God wants for us, which is nothing but goodness.
We learn to accept all things that come as from the hand of God, whether it is giving or taking, whether it is times of plenty or times of lack, whether it is times when we are honored or times when we are shamed and humiliated, we thank God for all He provides knowing that all things work for our eternal good. To have the presence of God, His supernatural peace and inner joy, and a kind of abundance that cannot be counted in monetary ways, is an inner strength that enables us to endure incredible trials, not without struggle and pain but with a certainty of God's goodness that cannot be shaken.
Being more conscious of the eternal helps us in the temporal and gives us a source of wisdom and strength that transcends circumstances and allows us to thrive and overcome even through maximum hardship. Not being consciously mindful in the moment allows for deception as the tyranny of the urgent often acts as a siren call to doom, tempting us into shortcuts or frustrated outbursts.
We are made to rule with God forever over His entire Creation, above the angels and animals and anything else that exists, we stand only below God Himself, and all the trillions of planets and stars will be reigned over by the Elect, among whose number one may only be counted if they have given their lives in faith to Jesus Christ.
Our eternity is set by how we live in this life. Every decision in this life that doesn't at least give a nod to our eternity is likely not a wise one. This is something you should meditate on extensively until you feel it deep within you until your instinct to think in terms of your eternity before doing anything is overpowering and directs your thinking unconsciously.
How would I live if there was no eternity and no consequences after this life?
This is a good question. Another way to ask it would be to ask, "if the results/consequences to this decision/action are limited only to this life, what decision/action would I take?" This is a balancing question, as often when something can be seen as being both beneficial to the temporal and the eternal it may be a solid clue this is a good choice.
But if there was no eternity at all, how would I act?
In truth, I would seek the maximum enjoyment and enrichment of myself and the people I love to enjoy this life as much as possible. My thinking would be more short-term, though I would probably still care about my legacy and about future generations, so the idea of only being concerned about your consequences in this life is probably uncommon among most people.
The balance here is that I often challenge myself to enjoy this life and not be so focused on eternity that I do not enjoy this life. Having a nice house and car are not a sin if obtaining them is not being done through sinful means to reduce this concept to an almost childish simplicity.
Indeed, enjoying this life and seeing relationships as the true brass ring of this life is essential to being prepared for eternity: these experiences of just enjoying this life and our relationships sow into who we become for our eternal destiny.