My dokter recommend the six minute diary. Think it's originally german (I'm Dutch but they have a Dutch one here, not sure of there's an English one). Three minutes in the morning, three minutes at night to fill in a couple questions about the moments of the day and gratitude. Some week questions about life here and there but I've really come to enjoy it. Also has a good built up of information about the scientific research before starting the actual six minutes a day.