There are a few different positivity spells around here on Spells8. Siofra linked some of them but I’ll add a few more here.
It would be helpful to know what type of positivity you’re looking for. If it’s just general positivity, the ones above could be helpful. I’d also encourage journaling and meditation to see if you can get to the root cause of a lack of positivity. Sometimes we just need to analyze what’s going on and invite that positivity in while dealing with whatever is getting us down.