Dear Izabelle, 

Here is a quotation from Fr. Maciel the founder of the Legionaries that I really like: 

"I can assure you that no other happiness is authentic, no other happiness is lasting - the only happiness that is lasting and the only joy that is authentic is to find that you are fulfilling God's will for you. This is so because if you are doing what God wants it means there is love in your heart, and love unites us to him, and union with God gives us peace. If there is no peace there can be no authentic happiness. People are set on trying to find happiness by letting their passions run free. They think that if they satisfy their pride, self-love and sensuality they will be happy, but when they turn around they find their hands are empty. Only God gives happiness because only God, your love for him, your union with him will bring peace to your soul." 

God bless,