With me it was something I just had to give into and have a go.
For years I felt the urge/energy to begin writing songs, but I think my main problem was that I did not see myself as a songwriter.
Having made the conscious decision to recognise the urge, after a few songs I too began to regard myself as a songwriter.
Songs can come from any source, any time, any where - or they may not come at all.
Oftentimes a song's source is something that just won't go away.