Well, it isn't a new penance, exactly. Since it comes to us from St. Francis, that means it's an 800-year-old devotion - but it feels new to me.
Saint Michael's Lent is a forty-day devotion (just like Lent!) that begins on August 15th and ends on September 29th. While the end date is not remarkable (in that the devotion must end on St. Michael's feast day, ergo St. Michael's Lent), it's oddly coincidental that it begins with one of the highest Marian feasts - the Assumption. It means that St. Michael's Lent is not simply a devotion to the Archangel, but is also a gift to the Queen of Angels, the Mother of God.
This year will be my first year practicing St. Michael's Lent (indeed, it is only my second year of even knowing that it exists). I intend to practice it by taking on a few of the Exodus90 practices - fasting and abstinence, significantly reduced screen time, and a daily holy hour (erm, maybe half hour...). Maybe the cold showers. While I'm a firm believer that every day is a day to grow closer to God, I look forward to this new season of intentionally renewed fervor.
And if you're looking to increase your devotion to St. Michael in another way, go check out my St. Michael Prayer Art Print.