For Repenting of Lent and its disciplines, read here.
For Why Lent Matters, read here.
Personally, I find the idea that Lent harms your spiritual life not only mildly amusing but typical of the pietistic idea that inward heart things matter and external things don't. What is so ridiculous here is the idea that Jesus supports such a viewpoint. Where does Jesus ever condemn the Pharisees (the kings of outward piety) for the things they do (fasting, prayers, almsgiving, etc. . .)? In fact, Jesus lauds their righteousness and insists that unless your righteousness EXCEEDS that of the Pharisees, you cannot enter the kingdom of heaven. What Jesus condemns is not what the Pharisees do, but what they fail to do -- the faith (trust) that is behind these external acts of piety and faith. The condemnation of Jesus is that the external actions of the Pharisees are ONLY external works, absent any real faith and trust of the heart.
The Gospel reading for Ash Wednesday (Matthew 6) can only be construed to condemn external acts of piety and faith IF they are in place of the faith that (Romans 4-5) is credited as righteousness. For some time now I have wondered if this is the right Gospel for the start of Lent since our problem is hardly one of too much external piety but a worldly piety which makes a Christian look too much like one who does not believe. But that is for another to determine. Jesus never once disdains the actions of this piety but only that these actions are devoid of trust in God's grace and confidence of His mercy through faith.
One Roman Catholic source listed the Lenten requirements for the faithful in 1873:
(1873) REGULATIONS FOR LENT.
Ash Wednesday, the first day of Lent, will fall on the twenty-sixth day of February.
1. Every day during Lent except Sunday, is a day of fast on one meal, which should no be taken before mid-day, with the allowance of a moderate collation in the evening.
2. The precept of fasting implies also that of abstinence from the use of flesh meat, but by dispensation, the use of flesh meat is allowed in this Diocese at every meal on Sunday, and at the principal meal on Mondays, Tuesdays and Thursdays, of Lent except Holy Thursday.
3. There is no prohibition to use eggs, butter or cheese, provided the rules of quantity prescribed by the fast be complied with. Fish is not to be used at the same meals at which flesh meat is allowed.
Butter, or if necessary lard, may be used in dressing of fish or vegetables.
4. All persons over seven years of age are bound to abstain from the use of flesh meat, and all over twenty-one to fast according to the above regulations unless there be a legitimate cause of exemption. The Church excuses from the obligations of fasting, but not from that of abstinence from flesh meat, except in special cases of sickness or the like, the following classes of persons: 1st, the infirm; 2nd, those whose duties are of an exhausting or laborious character; 3rd, women in pregnancy, or nursing infants; 4th, those who are enfeebled by old age. In case of doubt in regard to any of the above exemptions, recourse must be had to one’s spiritual director, or physician.
All alike, should enter into the spirit of this holy season, which is, in a special manner, a time of prayer, and sorrow for sin, of almsgiving, and mortification.
The faithful are reminded that by a special privilege granted d by the Holy see to the faithful of this Diocese, a Plenary Indulgence may be gained on the usual conditions, on St. Patrick’s Day or any day, within the Octave.
Compare this with what Roman Catholics do today? or Lutherans? We are hardly in danger of being too pious during Lent. Ours is not a problem of too many external acts of piety; just the opposite. We do little or nothing -- not during Lent and not otherwise. Now I am NOT recommending that we adopt these rules for Lent nor am I suggesting that any rules be adopted for Lent. What I am saying is that the idea that spiritual disciplines during Lent are harmful to our faith is absurd.
There is no mention of Jesus ever questioning or challenging regular worship in the Lord's house, a life of daily prayer, reading and studying the Word of God, almsgiving, fasting, external marks of inward repentance, or anything else. Our Lord does not challenge the actions but the actors -- those who keep the rules without a heart of faith. They are the hypocrites who rightfully should be challenged -- not the pious Roman Catholics or Lutherans or other Christians who desire to do these things as part of a spiritual discipline of faith during the Lenten season.