In my opinion, the discussion of the quest for Qi and/or Internal Strength is a major waste of time. It is, in my view, generally engaged in ad-nauseum by people who have neither and have no real concept or experience of either. This, in my opinion, is because they have not invested the effort and sweat in the fundamental training that comes before learning basics and is prerequisite to skill. From what I have seen, martial arts training in the West and (sadly) much of the open to foreigners training in China these days consists of learning some basic stances and hand movements, then on to drills or forms, followed or accompanied by "applications" training or kickboxing flavored sparring. This is not how real martial arts were traditionally taught. The foundation skills, the things that my teachers spent 2 or 3 years on before being taught forms and such, are for the most part no longer publicly taught. In part this is because teachers are either less fully trained than the generations before them and are themselves ignorant, or because they are teaching what students ask for. In either case, the students and the arts are given short shrift.
My Yongchun and Lohan teachers both told me in great detail what their first couple of years of training were like. My Lohan teacher was fond of pointing out that we, his students, would never reach his level because we were unwilling or unable to devote the time and effort and pain needed to get the foundation skills that he had. At the time I thought he was just using this to goad us - but I now see that he was right.
What do I mean by foundation skills? A vast series of exercises designed to stretch, strengthen, develop balance, agility, and endurance. These included exercises with weights and other equipment, as well as myriad deep stance and mobility exercises, jumping exercises, and what might be considered as basic gymnastic maneuvers. Not until one had this foundation firmly in place could on go on to learning the movements, techniques, and usage of the system - but progress would be relatively fast, as the foundation skills would find expression in the movements and applications of the system. As for Qi and "internal strength"? To some degree the Qi would manifest itself as a result of proper training, and Internal Strength was already being laid down with the foundation work. Trying to work in the other direction is like trying to run water through weak and rusty pipes.
A casual stroll through the lunatic asylum shows that faith does not prove anything.