One of the most challenging things Paul said was in Acts 20:24 "I consider my life worth nothing to me..." (NIV).  I read mainly the NASB translation of the Bible today, but I learned this verse in the NIV and as a teenager I was so challenged by what Paul said there.  What a challenge Paul gave us in his example.
We can tell a lot about ourself by what pops up in our phone apps and on our computers, in our web browsers - Recommended videos, and ads, etc.  Companies spend billions to track our behavior and recommend us content they think we will consume.  So in a sense I suppose at least some of what comes back to me is a reflection of myself - and my interests.
But I was surprised the other day that Youtube recommended me a really random video, I have no idea why.  The video was a live stream of a memorial of a random lady who had recently passed away a day or two earlier.  This was not a famous lady - it was an older woman who lived in the U.S. somewhere, and the funeral home where her service was had a Youtube channel which livestreamed the services.  And for reasons unknown to me, it popped up in my recommended videos.
At first I was confused and ignored it, but then I was reminded of Ecclesiastes 7:2 : "It is better to go to a house of mourning Than to go to a house of feasting, Because that is the end of every man, And the living takes it to heart."  So I clicked on it and started watching.
There's something valuable about remembering death, and thinking about it.  When we think forward it urges us on to live a worthwhile life now.  And when I stand before God, I'll definitely at that time be thinking about how I wish I had lived.  But the wise ones are the ones who consider that question now, and not just consider that question, but they do something about it (see the parable of the wise and foolish virgins in Matthew 25).
So I clicked on that live stream (which had been going on for a little while already - so I scanned through it), and I watched family members talk of this womans life - the challenges she went through, losing a husband who died somehow when the kids were young. Trying to raise her daughters in the right way, and be there as a support to her grandkids in the midst of everything.
But the thing that touched me most is what her granddaughter said.  She said weeping, “I wish I could have told you more how much you mean to me.” And I thought of people that have passed away in my life, and how we definitely often have that thought: "If only I had one more day..."
But then I realized something even more important on the exact same lines, but not toward loved ones.  Toward God: we have JUST this one life to show God how much He means to us.
And here's the question: When I come to die (or the Lord returns first), will I say, "I wish I could have showed the Lord more how much He means to me."
And it flips my perspective on everything when I think like that.  How much more I wish I would have strove against sin harder in my inner life, to spend plain and simple time with Him - not with masterful professional prayers but just 2 friends alone with each other - Jesus and I.  To love Jesus by loving others and showing them mercy and encuragement, to be content in all trials and suffering for His sake, to praise Him in them.  To labor WITH God for salvation of others by praying for them and never giving up, to seek His presence always, and treasure Him above all.  To despise the things of earth, and to consider everything of earth rubbish for His sake - to know Him and to please Him.
What a chance we have now.  But we only have it now. 2 Cor 6:2 "... Behold, now is "THE ACCEPTABLE TIME," behold, now is "THE DAY OF SALVATION"
I've heard it said, "A man is what the thinks about all day."  One of my goals in this life is to gain the continual habit of gently turning my attention away from distraction and back to the Lord and His presence, throughout every day.  Not to fix my gaze on 'other cares'.  It's not easy. I don't think many Christians ever attain that type of closeness with the Lord.  But the Lord put in my heart the desire for that life, and I believe that this is the way to keep doing everything for the love and glory of God (1 Cor 10:31) - to carry my cross with Jesus in my sights (Heb 12:2) and in my heart.  Otherwise it's like a wife who cooks and cleans the home, and doesn't leave - but has no desire for her husband, no intention to love and be with him.  It can be lifeless.  I have to keep the Father and Jesus in my heart in the midst of all of this.  I need the right life WITH the right motive.
The Lord gave me a picture one time: I like to drink coffee in disposable cups.  I enjoy the coffee.  But the cup is basically value-less except for what it holds for a temporary time.  I throw it out after. And I saw - that is EXACTLY what our life is: Disposable.  That's what Paul said "my life is worth nothing to me..  if only I may finish my course" (Acts 20:24). The only value this life holds is what it can contain of Jesus in this passing moment that we are here.  It's disposable.  It's a disposable life - but can be full of treasure while it is here for a little time, before it's thrown out.
Our disposable life can be a cup full of devotion to Christ - devotion means : Christ is EVERYTHING to me. That devotion is the valuable thing this disposable life can hold for a time.
The disposable cup full of Christlikeness to live here and please the Lord not just outwardly, but inwardly from the heart with pure love and intentions flowing out of us
The disposable cup full of humility which lifts the Father and Jesus up, and is happy to go down and decrease because He is increasing
The disposable cup full of trust and faith which bows before God's wisdom and love, in the midst of great pain and years of suffering - contently committing ourself to the Lord's hand through it all to do as He will
This is the eternal value which our disposable cup can hold for some time until we take it into eternity.
James 4:14  "...You are just a vapor that appears for a little while and then vanishes away."
And it is spiritually very helpful - thinking about the future and our end (even in the form of watching Youtube memorials of strangers!) - to meditate on: what will matter 1000 years from now? Or even 100 years from now?  This helped me early on in my Christian life.  And I'm working to try to teach my kids about this today.
Here's a poem which also challenged me when I was younger and I heard it - to live more seriously for God now, and to fix my mind on things above (Col 3:2):
It will not make much difference, friend,
A hundred years from now,
If you live in a stately mansion
Or on a floating river scow;
If the clothes you wear are tailor-made
Or pieced together somehow,
If you eat big steaks or beans and cake
A hundred years from now.
It won’t matter about your bank account
Or the make of car you drive,
For the grave will claim your riches and fame
And the things for which you strive.
There’s a deadline we all must meet
And no one will turn up late,
It won’t matter then all the places you’ve been,
Each one will keep that date.
We will only have in eternity
What we gave away on earth,
When we go to the grave we can only save
The things of eternal worth,
What matters, friend, the earthly gain
For which some men always bow?
For your destiny will be sealed, you see
A hundred years from now.