For the first year of my mindfulness practice, I cheerily recommended meditation to acquaintances who were struggling with anxiety and a lack of joy. After a harrowing experience of dissolution that lasted for several weeks, I realized that mindfulness isn't just calm and pleasant experiences. I still continue to practice and it does bring me joy but I no longer recommend this particular practice to anyone who has a rocky past and a limited support system and just wants to feel 'good'. For that, I think diet, exercise, and sleep are safe bets.