Punishments

Ropernrider​(dom male) - Hmmm.
Denial of orgasms for a pre determined period of time
Electric shock
Hot wax
Nipple clamps
Extra chores
Public humiliation (if legal)
Bondage an sensory deprivation for a set period of time (known only to you) and you leave her there alone (keep an eye on her from a distance so you know she's still ok, but don't let her know you're doing that.)
Piercing/needles
Anal hook/butt plug for certain ammount of time.
That's all I can think of for now.
Obviously these are all highly dependent on whether or not she finds them more enjoyable then painful or they won't work. Also have to take hard limits into consideration. But maybe that'll spark some ideas for you.

Belladonna Dreams​(sub female){Phage'Hada} - Some of those are a little extreme

ropefish - For me personally, disappointment is the most impactful punishment from a partner. "Funishments" are different. I like pain, I like being teased, so those don't give me a genuine sense of "I did something wrong".
In the past I've had time outs, time sat in the corner reflecting on what I'd done, and that really sucked for me, because I was so acutely aware of how I'd disappointed them.

....anyway, every sub is different. There's no blanket punishment that will be effective on everyone. I recommend thinking about the emotions behind actions. "Spanking" sounds like a punishment, but if it turns your sub on, then you're effectively rewarding bad behavior with pleasure. Instead, figure out how you want your sub to feel, and go from there.

OwnedByTheOcean​(masochist female) - Kneeling on rice with ginger taped to her anus..... just saying......

OwnedByTheOcean​(masochist female) - Just make sure the ginger is peeled first.... 😈

SSG{ENM-TLP} - If this is just about punishment, then what they said... but if you are really wanting her to change these behaviors then positively reinforce the behaviors you want to see from her. You can negatively reinforce them, too. Positively reinforcing is adding something that will increase the behavior, i.e. spankings, praise, whatever it is she really motivated by. Negatively reinforcing is taking something away that will increase the behavior, i.e. spankings, (I don't suggest withholding praise or love that is manipulative and abusive--unless that is your kink of course), pay attention to the things that she chooses to do a lot. Those are the things that reinforce her. The problem with the gym is the pay off of working out isn't immediate enough. It is a common problem for everyone. So make her payoff more immediate. While the payoff of weight loss or muscle gain isn't immediate, Your reinforcement can be. I'm happy to help if this was the direction you were wanting to go. If not, the rice and ginger is down right sinister. If that's her thing, she'll love it.

OwnedByTheOcean​(masochist female) - Well said! And agree 1000%! The rice and ginger are just because I’m hungry....

justwatching - I gave Daddy attitude once and I had to write “I do not give Daddy attitude” 60 times on paper and send proof when done. He said he was being lenient by only requiring 60 rather than 100. Lesson was learned.

TheLittlePrincess​(sub female){SSG} - I agree with RiritheSub. Writing can really make a sub think about the action that got them to the punishment and also just be time consuming and annoying to do. I suggest maybe having her write a paragraph or however long you think it should be to fit the punishment. Tell her to write about what she did, why it was wrong, and she can even get her feelings about it out. It's more of a slow burn because as she starts writing it, it makes the sub really aware of the mistake and why it was wrong.

Ropernrider​(dom male) - Interesting. I had never thought of writing in that way, good to know!

Writing lines in school was just more of an annoyance for me than anything. It never really did anything to correct my behavior or convince me I was wrong. I suppose it might depend somewhat on personality type.

TheLittlePrincess​(sub female){SSG} - Well, for me, doing it for school or anything like that never worked. But, if I mess up with my Domme then I already feel bad or guilty about it and I just want to do whatever to make it better. Writing would only make me focus more on it, which brings it more to the front of my mind. Of course, everyone is different. I personally don't care as much if I mess up to someone else, but if I mess up to my Domme then that matters a LOT to me.