Vesicles of amphiphilic block copolymers have been extensively studied, but surprisingly few studies used high temperature to promote the polymer shape evolution towards vesicles. In this work, we carry out a systematic comparison between the popular water addition method and the heating method, and the latter was found to have a much broader window of conditions giving vesicles. For most of the conditions we attempted, it appears that the evolution towards vesicles is largely limited by kinetics, though allowed by thermodynamics. Hence, heating is instrumental in promoting the process. We believe that this demonstration of simple concept would popularize the heating method and help vesicle preparation in this field.