Yes I think you can get yourself very worked up into thinking you will never be cured if you don't see results quick enough, in the 90 days etc etc.
However, it is important to remember that your brain is clever, it is making you think these thoughts to try and get you to relapse so you/it can get your/its dopamine fix.
Also, in your case remember that the length of time you've been using porn is only one of a series of factors in the strength of the neural pathways. Yes you've been using it for 40 years but they will be weaker if you are sexually experienced. So, don't let that part get you down.
One more thing, if your problem is more about the strength/frequency of your erections then that can be helped with kegel exercises, people generally report lots of success with those.
