Intrinsically, to practice "what you really need" is indispensable for you to master it. No one can master anything without doing so. It is common sense for intellectuals in the world.
To practice something is not only the meaning of practicing it as a layman but also the meaning of taking action as an expert.
A lawyer can be interpreted as the meaning of a legal practitioner who is professional enough. It goes without saying that legal practitioner is "not amateurish" at all. He is an absolutely learned professional.
My beloved disciples, I'd like to practice what you need not as a nonprofessional but as a professional who follows me through receiving transubstantiation from me. I'd like you to be proud of yourself as my disciple who aims to reach the ultimate in human intellectuality through receiving and experiencing transubstantiation from me for the sake of the realization of professional sophistication now and in the future.
I'd like you to make sense as one of sapient beings in terms of practicing so under the auspices of holy instruction I carry out at the risk of my honor, dignity and life in my 24 hours every day every night.