Pleasure arising from the stimulation of your senses is fleeting; however, happiness arising from your mind is long-lasting.
The difference between pleasure and happiness.
Pleasure refers to the enjoyment resulting from the stimulation of any of the five senses. Happiness can only be experienced through the mind, i.e., through love, compassion and generosity.
Pay attention to your mental level of joy and happiness.
Instead of focusing on the physical, material things that bring you pleasure, focus on the joy in your mind. One way to do this is to develop a strong sense of concern for the well-being of all sentient beings (particularly human beings) so as to develop a genuine sense of love and affection.
Meditate on compassion.
Meditating on compassion for others even for 10 minutes a day will help you maintain a calm and joyous mind all day long.
[OPTIONAL] Develop this joy through faith in God.
Having faith in God can bring inner strength and inner peace, which will lead to happiness. Alternatively, you can train your mind to achieve happiness.