I am going to say right off the top that there are some problems with both how the OP is framed and also with some of the responses within the thread.
Surely many of know and appreciate that there are needs for real world actions, and we cannot just use our minds to accomplish tasks or even to put ourselves into a position in which we are able to continue with a plan that we might have had wanted to carry out or maybe to have had started to carry out.
So, in that regard, I have a lot of doubts about whether any bitcoin related plan could be "purely" a mental challenge, even if there likely is a lot of mental component within any plan that we might attempt to carry out and to follow through with, including that sometimes whatever preparations that we might have made, to carry out the plan, may or may have not had been enough in order to put ourselves into a strong enough position as to follow through with what we had originally intended.
I would not even say that there would necessarily be any kind of absolute need to stick with a plan if the plan is not working, so sometimes there can be legitimate, rational and prudent reasons to actually abandon a plan that had already been started.
Part of any question might be to figure out what our plan is and then to attempt to both follow through with it and to learn along the way, so it could be that we establish a plan to invest into bitcoin for the longer term of 4-10 years or more and to follow a certain strategy to accumulate BTC in a variety of ways that might include lump sum buying, DCA and/or buying on the dip, but then we may also need to reassess our plan from time to time based on our individual financial and psychological factors, but also may have to do with our view of bitcoin.. what did we think about bitcoin when we started to follow our investment plan, and did something about bitcoin change in the process of following our plan that would either contribute to our need to reassess our following of the plan or to tweak the plan or to abandon the plan.
Sometimes bitcoin HODLers will wrongly conclude that either there is something wrong with bitcoin or that there might be some kind of a need to sell BTC when the price is dropping in order to either buy back at a lower price or to just save themselves from losing more than they had initially planned to lose. Many of these can be mental challenges, but they are also challenges of putting systems in place that might be aggressive, but not so aggressive that it fails to prepare for BTC price moves in either direction, including extreme BTC price moves that go beyond expectations (which we also know happens in BTC from time to time).
Ultimately we seem to get into a place in which we cannot really have strong assessments regarding how we might act in certain circumstances if we have not gone through a certain level of planning it out, preparing for price moves in either direction, but also engaging in kinds of investing into bitcoin that might border upon aggressiveness but does not go so far as to devolve into gambling, and sometimes if we are not sure about how aggressive that we might be able to be with our bitcoin investment, then it might be better to employ a more whimpy bitcoin approach in order that we don't contribute to our own feelings of stress in the event that the BTC price ends up moving against what we thought that it would do (which largely means going down in price rather than sideways and/or up).
Most of the holders don't have that mental strength to keep on holding. And when they see the price dropping, they sell in panic.
Yeah, maybe we say it easily right now "let's HODL for a very long time" but it's really a different situation, once our stash of Bitcoin has hit 1 million US Dollars or even more. It will be very tempting to sell because after selling it, we would be insanely rich.
So, we can see, it's not easy at all to be a good HODLer.
In any case, I would always try to keep at least a fraction of Bitcoin.
Never sell everything.
In any case, I have been holding for some time. Quite a bit of time. Around 85% of everything I earn is in my holding account. The rest I am somehow using to survive. I need to sell, because I need money, I need to buy things, but I'm holding myself back. Wait just some days. I know it may sound absurd. But I think if I can somehow pass this moment, I can hit a big. That's why I have been buying whenever I can. As we all know, we are at the peak of bitcoin. The halving will occur pretty soon, in April 2024. So until then, I will keep buying.
Never selling everything, almost holding everything.
You have some good ideas, but it also sounds to me that you have likely put yourself into a status of being over-invested in bitcoin, and you have a bit of a gambling mentality in which you are planning to cash out some of your BTC at a certain point in time after the halvening, while at the same time you don't plan to sell all of your BTC... so you are surely wanting to try to play the waves that may or may not happen and it may or may not work out for you.. though it sounds like you have a decent amount of patience and attempts to plan through some of the potential waves.
Within reason, I personally don't mind the idea of overly investing into bitcoin, but each of us needs to try to make sure that we have our emergency funds covered and our cashflow, so that we do not get into a financial and/or psychological pickle because we had been overly investing into BTC.