I grew up with the saying drilled into my head over and over again:
Don't do something just for the sake of it.
It was usually followed by 'Put your heart into it' or something similar.
This advice is very popular and people start nodding in agreement, as soon as you start saying the first line, the second line completing in their head.
I threw this line around a lot, myself. Especially, when I liked giving gyan (unsolicited advice).
I'm finding a deeper truth in an alternate meaning, formed by shifting the same words around.
'Once you have your heart in something, do it just for the sake of it.'
It may lead to something. Or it may not. Regardless, it would be fun; which, probably, is the end goal.