I usually start up with good work on any problem, working on for its solution. But the problem with me is that I'm unable to work on and on deeper into the solution. Just when I arrive at something worth of a solution, I somehow don't get the motivation to proceed further. This is making my life a hell as I'm unable to finish any task properly. this happens not just in my studies but in personal life too. I do understand that for a phd student, stability is of utmost importance. How do I work on to improve this.

I do it in a kind of excitement I Believe that 'Now this is Achievable' and forget about it next day. Do you in excitement or despair?

I'm excited when I start the work but the excitement level gradually goes down. If I don't like the work, I won't start it at all...