Lent has been formally observed by Christians since the 4th century, but the practice of fasting, repentance, and prayer before Easter has been observed since at least the 2nd century according to the testimony of St. Irenaeus. Easter has always been a time of celebration for the church. On Easter we remember the victory that Christ won through his resurrection; we celebrate the fact that he overcame death, hell, and the devil by conquering the grave, as he burst forth from the tomb. But times of great joy in the Christian tradition, such as Easter or Christmas, are preceded by contemplation, repentance, and prayer.
The forty days in which fasting is practiced before Easter mirrors the forty days that Jesus spent in the wilderness (Matthew 4:1-2). The practice of forty days of fasting goes back even farther, as both Moses (Exodus 34:28) and Elijah (1 Kings 19:8) used forty days as a means for spiritual preparation. In the same way that these great saints took time out of their lives to focus on prayer, and fasting, and in imitation of Christ, we too utilize this spiritual practice.
In certain traditions, fasting becomes legalistic. Certain churches, bishops, and pastors, require fasting for these forty days, and at times even dictate what your fast should be. Instead of a free decision, fasting becomes compulsory, it is made into a strict Law. This is opposed to the Gospel. St. Paul writes to the Colossians, “Therefore let no one pass judgment on you in questions of food and drink, or with regard to a festival or new moon or a Sabbath.” (Colossians 2:16) We are no longer bound to a Law which dictates what we can and cannot eat or drink, or what days we need to celebrate. Those ordinances of the Old Testament were pictures of Christ, which no longer have any hold on us because Jesus has fulfilled them. We have freedom in Christ.
Does this mean that we shouldn't observe Lent because God doesn't require us to? We would do well to listen to the wisdom of St. Paul on this point. “ 'All things are lawful, but not all things are helpful.” (1 Corinthians 10:23) Even though we don't need to observe Lent, it is helpful to do so. As Christians for 2,000 years have used this time as a means to focus on repentance and fasting, we too would do well to do the same. Focusing on repentance, and taking time to meditate over our sin is helpful because it allows us to more fully understand the joys of Easter. A recognition of our sin always comes before the proclamation that our sins are forgiven. We only rejoice in God's forgiveness if we understand the truth of our great offenses against God.
There are different ways in which Lent can be observed. Some choose to fast from food from sun up to sun down; others choose to fast from a certain meal each week, or choose a 24 hour period to fast; many will give up some sort of habit or food that they usually indulge in. There are also spiritual practices which some take up such as praying the Psalms, setting aside a longer time of prayer than is normal during the rest of the year, or having a plan to read through more Scripture each day.
I would encourage you to observe Lent this year, not in a legalistic way, not because you have to; but do so because through it you will be edified, and through contemplation, prayer, and fasting, the Gospel will become even more joyous when it is proclaimed boldly on Easter morning.