Absolutely confess the denial, especially as it weighs on your conscience. A general confession. while mainly for mortal sins, certainly can cover venial sins, as well. Pray to the Holy Spirit and use a good examination by way of the 10 Commandments to reveal to you the ways in which you have not acted in accord with God’s will during your life, or have failed to act in accord with His will during your life. For example:
FIRST COMMANDMENT: I am the Lord your God. You shall not have strange gods before Me.
Have I refused to surrender myself to God’s Word as taught by the Church?
Have I received the Blessed Sacrament after having broken the one-hour fast without just medical reason?
Have I failed to avoid the near occasion of sin?
Have I put love of God second in my life, behind love of something(s) of this world: rest, entertainments, money, image, looks, clothes, popularity or selfish desires?
Have I been ashamed to speak of God to others?
Have I exposed myself to the danger of offending God by the company I keep, materials I read, or media I watch or listen to?
Have I put myself first before God, and been too full of pride?
Have I truly loved God with my whole heart?
Have I failed to respect God in times of prayer, or have I just ‘gone through the motions’?
SECOND COMMANDMENT: You shall not take the name of the Lord your God in vain.
Have I blamed God for my failings?
Do I hesitate to mention God’s name in appropriate situations, in conversations with friends and family members?
Have I behaved disrespectfully in Church?
Have I watched television or movies, or listened to music that treated God, the Church, the saints, or sacred things irreverently?
Have I sworn by God’s name (taken an oath) either falsely or rashly?
Have I broken any vow or solemn promise made to God?
Have I made a rash vow, without sufficient knowledge or deliberation?
THIRD COMMANDMENT: Remember to keep holy the Lord’s Day.
Have I missed Mass Sunday or a Holy Day of Obligation carelessly or through my own fault?
Have I set aside Sunday as a day of rest and a family day?
Do I participate in the Eucharist by praying and singing, or do I simply sit and wait to be entertained?
Do I pay close attention to the Word of God and open myself to God’s call to allow His word to take effect in my lives?
Have I caused others to do work on Sunday without necessity?
Have I done unnecessary work or shopping on Sunday?
Have I spent the better part of a Sunday or a Holy Day in temporal affairs?
Have I knowingly eaten meat on a day of abstinence?
Have I neglected to spend a considerable part of Sunday or a Holy Day in reading and praying, or have I not taken care that those under my charge do likewise?
Etc., etc., etc.
You can find many fine examens online, just do a search for them.