Abstract This chapter introduces recent developments in the thermomechanics of active systems, which exhibit features that are very different from those of equilibrium systems. This has many implications for systems ranging from shaken granular gases to the motion of cells. We start with a short overview of different definitions of pressure and the conditions under which they are equivalent. This allows us to identify a class of systems – commonly referred to as dry active matter – where the simple equilibrium intuition might break. We show that there is, in general, no equation of state for the forces they exert on their container. We discuss the origin of this phenomenon, as well as its consequences. Finally, we go beyond the question of the equation of state and provide a brief discussion of recent developments concerning the forces exerted on objects immersed in active systems.