I have mentioned in several posts about an online course I just finished called "The Science Of Happiness" The only reason I keep bringing it is because it has helped me on so many levels, from self-acceptance to mindfulness to positive thinking and finding the goodness in myself and others.

The course is just about over but you can still take it as a self-paced practice in everything I mentioned. There are lecture videos, exercises, discussion forums and many links to other resources if you wish to get deeper into any of the material covered.

No I don't work for edx.org I just found it to be truly helpful when I was at a low spot in my mental health issues.

There is also "Resilience - Becoming a resilient person" which is mainly lecture videos and takes only a couple of days unless you do the exercises of teaching what you learn to someone else. Once again I found this course to truly help with my mental health issues.

These courses are put on by the likes of Berkeley, MIT, and Harvard so the quality is there.