Sangharakshita gave this talk in 1975 - so, a looong time ago; and I probably listened to it for the first time in 1988! But I still think it is a really useful talk and worth listening to. I referred to this at Exeter Sangha Night 8 March, and talked about how this talk really got me to think about the purpose of what I was trying to do. 

And in addition, listening to this talk marked the start of learning to be creative and appropriate in my practice - really taking myself and my current mental states into account and looking for the most appropriate spiritual practice for me, at that moment in time, that would raise my level of consciousness to the more open, the wiser, the more compassionate. 

There is also a transcript of this talk available on freebuddhistaudio, link here