None of these other methods will work. Even a person with the strongest willpower might one day want to sell their Bitcoin. That's why if you want to hold your Bitcoin long-term, send it to the wallet of someone you trust and agree not to get it back before a certain period. Another alternative is to send it to an address you created, store the key on a flash drive and put that drive somewhere you can't easily access. After a certain period, you can go there and get it back.
There's no other way. If your Bitcoin is somewhere you can reach easily, there's always a chance you won't be able to resist selling it.
if that is the case might as well use multi sig so you the other person can't just randomly sell it when they want to and scam you
the point is that you should be able to fight yourself when you want to sell your bitcoins when it is not needed yet
you can and should sell your bitcoin when you need to but if it is not needed make sure to stop yourself no matter how much urge you get