The type of legal drugs you are asking about are prescribed by your doctor. There is no legal drug (mind altering substance) other than tobacco and alcohol, both depressants, that will work.
You could consider chocolate and sugar, both of which have the reputation of being ‘happy’ substances. I think your best bet would be a well balanced diet with lots of fruits and vegetables, drinking at least 6 to 8 glasses of water, enough exercise, and enough sleep would go a long way to the natural release of your happy life.