What if your deathbed self was a kind of magical stranger that could whisper in your ear as you lived your life? What would they say?
Mine would probably grab me by the shoulders and shake me awake, "Wake up! What are you doing?!? Are you seeing all this?! Do you realize how lucky you are?! Open up! Don't be so stuck on yourself!"
Most of the time we cycle through predictable, narrow, and self-centered loops. We have the same basic concerns, even if the specifics vary.
Most people are mostly going through the motions of their lives. There are a handful of well-worn patterns of thought, feeling, and action that cycle over and over each day. If you closely observe yourself for a few days, you will be surprised to discover how repetitive you are. Further, if you have sufficient awareness to observe yourself over longer periods of time, you will find patterns that repeat on various time horizons. Some patterns are seasonal, others are tied to various annual events.
Generally speaking, moments that are most meaningful are those in which we are present enough, attentive enough, to actually have new experiences. To take in fresh impressions of ourselves and the world around us. Youth is often seen as the time when we are most alive, as we have yet to settle into these patterns of perception and expression.
Imagine that you are lucky enough to be lucid in the days leading up to your death. You are laying in bed, too weak to move much, and are dropping back in time into moments of your life.
The mundane makes up a large amount of our time alive, and no person lives without their share of drudgery (at least I think so). Yet, it is possible to live each day in a way that our deathbed self will be content with.
These need not be high-drama, sappy notions of what is meaningful. You don’t have to quit your job and climb a mountain or something. Listening to a beautiful song. Watching birds dance. Tasting something sweet. Feeling the heartache of another. Holding the hand of a loved one. Taking pleasure in putting socks on your feet. All these and even more simple things can be meaningful from the deathbed, provided our attention is sufficiently engaged with what we are doing.
How might the contours of your day to day life change if every morning for a month you spent one minute contemplating something you could do that day that would seem meaningful from your deathbed?
There would probably be more kind exchanges with other people and less screen time. More appreciation of simple pleasures and beauty, less resentment over minor inconveniences. More love, less fear. 
And that’s the tragic thing: most of what deadens us to life, what mutes our aliveness, is fear of death. This is the principle that what we do to avoid a fear brings that fear about. A fear of rejection can have us be reserved and guarded, which has the effect of making people around us less comfortable and more likely to reject us.
Here’s the power of deathbed thinking: when we minimize the influence of fear over our choice-making, we tend to make more life-affirming choices. 
Unfortunately, recognizing this propositionally is usually not enough to make a difference. In the same way knowing that a healthy diet and an active lifestyle are good for you doesn’t make you fit.
For this perspective to make a difference, it needs to sink in deeper than just hooking into some cliche like “life is short”. We need to apprentice ourselves to the total process of existence, which includes death and decay. Entropy is all around us. Paradoxically, the more attuned you are to the pervasiveness of death, the more fully you can live. It fuels an urgency that we lose sight of amidst too much comfort.
The contemplation of death is something many wise people advise. Just as freedom is the study of slavery and happiness the study of suffering, living fully involves the study of death (and the ubiquitous “death-in-life”).
I come to live fully by understanding the ways I deaden myself to life.
 This is a good heuristic for maturing gracefully: more love, less fear.
 There is some subtlety here, as there is a place for fear and a level-headed assessment of risk. This is not what I’m speaking about here...e.g. doing some bold/risky behavior that has a high chance of causing bodily harm. I’m talking about more subtle and abstracted fears (like not living up to some barely conscious, idealized self-image that was implanted in us by some movie or advertisement we watched when we were young).