We studied the spectral behavior of a probe transmission in the presence of a counter propagating pump beam for various laser polarizations and magnetic fields with and without the assistance of an additional repopulation laser beam. These parametric studies enabled us to distinctively extricate the influence of saturation, optical pumping, and resonant light pressure. The enhanced probe absorption resulting from the pump-beam-induced Zeeman sub-state ressing was maximized when the change in the resonance frequency was suitably compensated by the change in the Doppler shift arising from resonant light pressure. The possibility of tuning the laser frequency locked to saturation absorption spectroscopy was investigated and implemented to a laser cooling and trapping setup.