Catholic Church traditionally maintain and preach the position that one should REPENT FOR HIS SINS, but on the contrary psychologists advise people NOT TO WORRY. (For example- “How to Stop Worrying and Start Living” written by Dale Carnegie.). Could you explain please "What is the difference between worrying about past sins and repenting for past since??. All Christians might find it useful the answers to this question since too much worrying for any thing would put ones mental health at risk and knowing to repent without worrying protects mental health, enable positive thinking and finally build a good and happy Christian whether Catholic or non Catholic.
To repent is to recognize that I did something wrong, make reasonable amends, and commitment myself to avoiding it in the future.
To “worry” is to constantly carry the weight of the sin on our minds, hearts, emotions, etc. no matter what. It is almost a refusal to accept forgiveness for the sin.
Repentance is a good thing and helps us to better appreciate the love and mercy of God. To constantly “worry” and keep the sin in the forefront of our mind can paralyze us from embracing God’s love and mercy and making full use of His grace to live better.
While I’m not sure I would say we shouldn’t “worry” about sin, I would say that we should never let something prevent us from embracing God’s love, mercy, and grace in our lives. Excessive worry can lead to scrupulosity.