Hi! "To enjoy the grind" means "to love/enjoy making progress (every single day). Tony Robbins sometimes uses this phrase in his videos. I think it's a common phrase.

Thanks, Mr. Wiliam

https://www.merriam-webster.com/dictionary/grind Grind noun 2a: dreary, monotonous, or difficult labor, study, or routine the dull grind of office work So.. in this case probably enjoy "working out" or enjoy doing something that will somehow help you improve yourself. Never heard of it before, but seems to be a common enough phrase on google.