Getting ECs and extra tips for college apps?

I’m a junior right now and I’m 16 and I’m finally eligible to work in most places.
With sats right now and school I barely have time to volunteer let alone get a job, however colleges love rigor so I’m wondering what type of job is best?
Is fast food working enough? Should I just stick with volunteering a lot? If not what’s a good job for my age? And what are some good ECs you can recommend? Thanks!