I only notice my overplaying when I hear a recording, and then it's cringe-time
What seemed tasty and groovy when I played it is often revealed on playback to be distracting or groove-killing or treading on the vocalist or soloist. Like I'm trying to talk over them, like those annoying people sitting behind you at the movie theater who are carrying on a conversation while you're trying to watch the movie. Or sort of stealth-showing off. That's when I cringe the most.
So, as others have suggested, recording yourself is the quickest way I know of. Record an entire practice and then listen to it over and over, and you'll soon get sick of your own pet fills and mannerisms being repeated over and over.
Limit yourself to using a particular lick only one time in a song, because the more you repeat it, the less it works and the more it starts to sound like an affectation, or like it's the only lick you know.
Limit yourself to only adding fills in a single verse or chorus. When you hear the playback you'll be most proud of the verse where you just lay down a solid foundation without any frills, creating a monster groove. Also, don't be adding fills when others are also adding fills. Usually bands work out who's supplying fills on which verse. Bass fills don't necessarily have to "scheduled" in the same way, but you must always yield to the designated fill-er. And of course to the vocalist or soloist. Don't risk pulling the listener's attention from them. That's not your job.
In the long run, it's a matter of maturity, which I guess it why I'm still struggling with it even though I'm 60 years old. I can't pretend that I don't like to rip off an "impressive" fill when I think I can get away with it. But on playback it almost always sounds gratuitous and selfish and cheesy.
One beer tastes better than 12 beers, yet I've drunk beers 2-12 trying to replicate the flavor of that first sip and regretted it later. Fills are often that way, too. One good one played once sounds better than 15 good ones in the same song.
Imagine how you would ask someone else to play the bass part if it was a song you'd written and you were the vocalist or soloist. What would you want them to focus on and what would you NOT want them to do. You don't want them to clutter it up or be constantly sneakily drawing attention to themselves, but to lay down a solid groove that you can work with--and sometimes against--to tell your story/weave your spell. The focus is on the story/spell, not on one member of the rhythm section trying to make the song his own vessel for personal expression or showing his chops/splendid harmonic sensibilities.
There are, of course, exceptions to be found everywhere, and the more chops/ideas you have, the more of a struggle it can be to not use and demonstrate them constantly. I'm still working at that mature restraint ("taste") and regularly going over the line.
One last thought--if your timing, including on the subdivisions of the beat, is not perfect, ANY fills will sound like overplaying. It's amazing to see how much playing some players (Jamerson, McCartney, Prestia, Jemmott, Rainey, etc) get away with at times because every note is rhythmically on the money, so it doesn't stick out like a sore thumb and kill the groove/break the spell. Come in late on a simple three quarter-note walkup from I to IV, and it suddenly sounds busy and cluttered.
Have fun. You'll figure it out. As others have said, the fact that you're aware of it says you've won 3/4 of the battle.
....It is hard to discipline ourselves at times yes
