As a non-catholic, but a medieval recreationist, I periodically observe Lent.
I found that giving up something was much easier than adopting a healthy habit.
I also kept my observation well within the scope of what I considered achievable - I didn't give up coffee or chocolate.
One year, I tried "eating 5 servings of fruits and vegetables each day."
Total fail. Maybe I will try again this year, with scaled down expectations.