It's not just singer-songwriter; it's not just two things. It's four:
1. composer of music
3. musician (guitar and/or piano, or whatever you perform with)
In the "old days", one person composed the music, another person composed the lyrics, a band of professional musicians played the music, and the singer sang. Sometimes it's still done that way today. Singer-songwriters are trying to do the jobs of 4 people. No wonder this is so hard. I'm not whining or complaining; I love it. But it explains why it's so difficult to be good at all 4 things (see my previous blog, "3 Types of Songwriters).
I began as a guitar player. Then I took singing lessons. Then learned how to write songs. Others do it in a different order.
I took piano lessons a few years ago, and took more last year. But my focus for the last 5 years has been songwriting (music and lyric composition). As a result, I'm starting to feel more confident in my songwriting. So now I'm taking singing lessons again, because I think that's my main weakness.
I've got 4 jobs. Not counting my paying job.
When I look at it that way, I don't call myself lazy anymore.