Ask HN: Do you use (and recommend) a fitness tracker?

I’ve been long considering buying a fitness tracker in an attempt to be more active and track progress with regard to activity. I’m already moderately fit but a serial procrastinator who is bad at planning.

I’ve been put off by privacy concerns, a feeling of “I don’t really need this” and wondering whether or not they are actually effective.

I’d be interested to hear peoples experiences with them and whether they have had a positive effect in their own right.