The secret to being happy? Conquer the passions. Make the body subject to the intellect.
When our passions rule over our intellect, we live like the animals. Our intellect tries to function and tell the body what reasonable things must be done and not done, but the body rebels. We are as slaves trapped inside our own body. What a poor, miserable way to live for a being created in the image and likeness of God!
The necessary medicine to avoid such a sickly lifestyle is daily acts of self-denial. Slowly but surely bring the body into submission by keeping the passions in check, and happiness will assuredly follow. When one is in control, when one maintains order between the body and the soul, well, that is the very definition of peace.
So start today by resolving to deny the passions in some small manner every single day. Make the passions subject to the intellect. When this happens, there will be known true peace, control, and yes, happiness.