Bolding keywords is good practice in terms of online copywriting, since it makes text more "scannable" - and remember that users don't tend to read all of your text. Similarly, if they search for something in Google and immediately see their keywords or related words in bold, they are more likely to see that the site is relevant.
But if you're bolding keywords just for the sake of it, and particularly if you're using a "checklist" style approach to SEO (e.g. same keyword in title, heading, URL, first paragraph etc. etc.) then you might want to consider a more natural approach.