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The prospects of using the upcoming high-intensity laser facilities has stimulated the interest in understanding the effects induced by intense radiation losses. This can guide the development of new experimental efforts, such as the creation of new gamma-ray sources for nuclear and quark-nuclear physics, as well as for mimicking and understanding astrophysical scenarios. We describe a universal theoretical approach for understanding and analyzing the dynamics of particles and plasmas in strong electromagnetic field of arbitrary configuration. We find that the intense drain of kinetic energy by radiation losses (in either classical or quantum form) leads to the tendency of particles to approach a direction that yields zero lateral acceleration (relative to their direction of motion). By deriving an explicit expression for such radiation free direction (RFD), we develop a closed description of both particle and plasma dynamics in this regime: at each point of space, the particles mainly move and form currents along the local RFD, while the deviation of their motion from the RFD can be calculated in order to account for their incoherent emission.