No, during Lent, do not do anything that would result in increased fatigue or decreased resilience: after all, you constantly live on the brink of overload, you must not exaggerate anything. And regarding those "sacrifices," do not do anything that would "overstretch" you or cause you cramping. The essential thing is that you remain open to the breath of the Lord God, where He makes Himself known, even where He keeps us in ignorance, and always with the certainty that He loves us. Surrender to Him every day, placing each day into His eternity.
(Card. Charles Journet /1891–1975/, correspondence)