Alright. About my hypothesis I talked about earlier. This morning I realised I have been living less cheerfully (and positively) ever since I started scoring poor marks in maths. Then I looked at the people who are good at maths - both in my age group and those older than me. They are relatively easy to approach and joke with.
Now my sample space might be too small to reach to a general conclusion but so far it seems to line up with my hypothesis.