I agree that there are certain things we should give up for good. Things that we are addicted to. Things that have become like an idol for us. Things that distract us from our relationship with God. We should be working on those things anyway, not because we are trying to earn God's favor, but because his grace has changed us.
Lent is about being intentional, and having a more intense time of self-denial. It's like the time when Jesus went into the wilderness. He took an intentional spiritual journey for a certain period of time. We need this from time to time, and Lent is the time that the Church has designated for us all to do it together (or at least at the same time). So, why Lent? It's a way for us to experience the Gospel story in a hands-on, experiential way. The Good News is more than words. Self-denial keeps us in touch with Christ, and helps us know some sense of solidarity with those who do go without food and other things that we can take for granted. Hopefully, Lent and the practice of self-denial cultivates your character, and puts you in touch with the work of Christ this Easter.
Feel free to share in the comments why you practice a holy Lent.