Sparring can be a complicated subject. Depending on what martial art you are practicing, who your teacher is, and who your fellow students are, sparring may not be a training goal.
Different arts (and their instructors) have different training goals, and learning how to fight may not be one of them. In my martial arts travels, here are some of the reasons I've heard regarding why people practice their martial arts (in no particular order):
"I like how it makes me feel."
"My parents are making me."
"I like the people."
"The price is right."
"Because one of the characters in Avatar: The Last Bender used a meteor sword!" (Probably one of my favorite responses)
"'Cause I like it."
Absolutely none of these have anything to do with fighting, practical self-defense, <insert trendy word here about how to punch someone else in the face>. And that's fine. If what you do brings you joy and doesn't break any laws, you don't have to defend it.
Question: So if you personally practice your martial art for one of these many reasons, how do you know you should be sparring?
Answer: If you've ever begun a sentence with "If somebody grabs / punches / kicks / bumps me, then I would use <insert impressive sounding technique here>".
As soon as you say this, you're fundamentally changing how you relate to your given martial art.
It's gone from "that thing I do" to "that thing that is going to keep me alive one day". And if that's what you're expecting your martial art to do one day, you need to start sparring. Now I'm not saying Google the nearest Smoker you can find and sign up. Sparring is not necessarily something you want to throw yourself in the deep end of and learn by doing. For most people with little to no sparring experience, the only thing you'll be learning is that people who spar more frequently than you can punch you in the face. A lot.
So what can you do? Here are a few tips: