General Training:
* Je m'entraîne. (Formal and informal) - This is the most common and literal translation.
* Je suis en train de m'entraîner. (Formal and informal) - This emphasizes the action of training.
Training for a specific activity:
* Je m'entraîne à... (Formal and informal) - Followed by the activity, e.g., "Je m'entraîne à jouer du piano." (I am practicing playing the piano.)
* Je suis en train de m'entraîner pour... (Formal and informal) - Followed by the activity or event, e.g., "Je suis en train de m'entraîner pour le marathon." (I am training for the marathon.)
Training professionally:
* Je suis en formation. (Formal) - This means you are receiving professional training.
* Je suis stagiaire. (Formal) - This means you are an intern or trainee.
The best way to say "I am training" in French depends on the specific context and formality of the situation.