I look sullen even when I'm not doing anything; would lip corner Botox be effective?

My mouth corners are naturally droopy, so whenever I just sit there with a blank expression, people around me keep asking if I'm angry. ㅠㅠ It's so stressful because as I get older, my cheeks sag along with my mouth, making me look even more grumpy. I've seen a lot of people on online communities who say their impressions improved dramatically after getting lip corner fillers or Botox. Does getting injections around the mouth hurt a lot? Haha. Also, I'm curious if there are any side effects, like my mouth not closing unnaturally when eating or talking! Please, those of you who have lifted your mouth corners and regained a gentle smile, leave some genuine reviews! ㅠㅠ