Theoretical physics foretells that "strain engineering" of graphene could hold the key to finding treasures still hidden in two-dimensional (2D) condensed matter physics and commercializing graphene-based devices. However, to produce strained graphene in large quantities is not an easy task by any means. Here, we demonstrate that thermal annealing of graphene placed on various substrates could be a surprisingly simple method for preparing strained graphene with a large area. We found that enhanced graphene-substrate interfacial adhesion plays a critical role in developing strained graphene. Creative device architectures that consider the thermal mismatch between graphene and the target substrate could enable the resulting strain to be intentionally tailored. We believe that our proposed method could suggest a shortcut to realization of graphene straintronics.