This Page here is highlighting some of the better courses that are offered for free by the world's best universities. These courses are ideal for students who would like to make the most out of their summer holidays, or if you are interested in a subject well beyond the syllabus you are studying. Completing these courses can be of substantial benefit to a good application to the best universities.
The Coursera Course the Science of Well-Being, is particularly famous and useful, not only academically, but also for helping you understand yourself better and can be found here:
The videos are not available without a VPN in some parts of the world, so the first week's worth are here. The English transcript for all of the videos is, however available everywhere, as are the assignments and assessments, as far as I can tell.
Week 1 - Introduction Videos click here