I just happened to swing by for a visit and and I saw this old thread of mine from almost 3 years ago had popped up again.
My own views and experience since then have continued to grow and evolve.
What I would like to offer up for consideration now is that some ordinary every day people who don't practice any form of cultivation can live well into their 80's and 90's while still being able to function reasonably well and still have pretty decent mental clarity. A smaller few even make it to the low 100's while still being able to get around to some degree and some still seem to have pretty decent mental clarity.
At the very least, the neidan practices I am familiar with are supposed to bring good health and also notably increase longevity (yes, in my experience those are some common claims made about the benefits of neidan practice), yet I personally don't know of many daoists in modern times who have done too much better than many ordinary folks in the health and longevity areas once they get older. Any 'spiritual' benefits beyond these more mundane benefits would be very hard if not impossible to quantify, but the basic achievements of good health and longevity well into old age don't seem to be too far above the average of 'ordinary' people.
That's not to say I think neidan practice can't help improve health and longevity, because I actually think it can, but just that I wonder if there really are many who truly achieve even those basic goals in neidan practice which would place them very much above the norm for health and longevity into old age. Some may well do, but it doesn't seem to be too overly many that I know of, anyway.
Therefore I would suggest that we should just feel blessed if we can truly achieve good health and mental clarity into old age, and also achieve true longevity above the norm if one desires that. Talk of 'spiritual immortality', etc., seems a pretty lofty goal when many don't seem to even achieve good health and mental clarity into old age beyond what is the norm.
In my view, if you can truly achieve and maintain good health and mental clarity well into old age, you would be doing very well indeed in your daoist and related practices.
I truly wonder whether we even really need any special 'spiritual' cultivation beyond just trying to understand self better and improve on our interactions with others, as certain schools of thought are that we are all 'immortal', anyway, and we are actually here experiencing this physical life 'dream' by choice made at some deeper level. I can't say for certain what is true or not true in that regard, but I am inclined in that direction.
At any rate, any practice that is really beneficial should, of course, have notable practical advantages for you over time.
If you just seem to be spinning your wheels, maybe it's time to do some re-evaluation.
Best wishes to all.