In an accordance with the hierarchy spiritus, anima, corpus (spirit, soul, body), we distinguish three types of ascesis, three types of self-control: ascesis of spirit, ascesis of soul, ascesis of body. Spiritual ascesis or mental ascesis is an ascesis of thoughts, a mental self-control. Ascesis of a soul represents control over character.  Bodily ascesis means control of action, conduct, and behaviour.
The key to a successful practice of ascesis is to practice in an accordance with the given hierarchy: Every impulse attacks first one’s mind in form of a thought. A bad thought leads to a character disharmony, e.g., desire. Yet the desire causes wrong acting (and not the other way). This is why the beginning of every successful ascesis is to suppress a wrong thought, a bad mental impulse.