Instability problem

Hi,
since several weeks i have instability problems: certain times i can do my activities with joy and passion, while some other i cannot, i start to think "why i'm doing this?".
For example i'm a runner, a chinese student, a guitar player and i also manage a website in which i read about trips, food and sometimes psychology. I'm passionate with bias.
I don't know why, i need to find the focus and for entire afternoons i can be absorbed, but other i can fell in a state of semi-depression.
Maybe because i live alone in a small house in the a little city.
In any case i cannot find the solution to this problem. How do you think?

Even during job, i pass from being bored to excited. In my point of view my horizon is too short and i cannot wait for having my reward