l think some times we have every think but we still sad and you dont know why My advice for read some Quran or listen to it and dont listen to music because it make you feel concern

the hobbies are not there just when you have the time but also and mainly when you feel sad. If you are sad, using one of your favourite hobby for relax. that's also simple

I think it's a popular feeling for everyone , even for men

Yes , that used to happen to me a lot but recentley i'm good and that feeling didn''t happen to me again and if it does i'll read quran to feel better because this is the best solution

i also feel blue without any reason,just calm down or take a walk