Lent can enable hypocrisy and self-deception.
(I've got ashes on my forehead. I'm acting sad. I'm giving up chocolate. I'll focus on these things instead of Jesus, and the besetting sins I'm unwilling to fight or shake off.)
Lent can be a tool to focus on Jesus' and our self-denial.
(Jesus humbled Himself. He endured the miseries and temptations of this life. I need to endure them faithfully, too. He laid down His life for me to be forgiven and pure.)