I feel like there is wisdom in "Make hay while the sun shines." When you're young and unencumbered by responsibility and family, when your cognitive abilities are at their peak, when your energy is endless, when your body is strong and healthy, when your knees work, and your fingers can type without arthritis: that's the optimal time to work and earn. Min-max that salary and stay healthy. Due to compounding interest,…
Based on my observations (so anecdotal probably), it seems that being happy doesn't depends on what you did in the past or what you intend your future to be, but what you're doing now. Looking bad at your younger self won't make you happy. Looking with envy at your older self won't make you happy. Regarding your comment, I've never found someone saying "I wish I did things differently" and being happy. The sheer fact…
I can be happy playing video games and relaxing, but maybe not fulfilled. I can work hard on interesting problems and feel fulfilled, but if that's all there is in my life I wouldn't say I lived well.
Confronted with death we look to our past for comfort. We're about to experience a total loss of everything and so, naturally, we search for meaning - "it can't have all been for nothing".
That's why the "death bed" thought experiment is interesting but also probably not the right way to frame things. It forces you to question life's intrinsic meaning and value but you should also think about how you feel right now, regardless of death or meaning or value.