(I'm kinda age regressed right now so I'm sorry for any mispellings!!)
I've age regressed impurely before and it's really not fun. once you're in that bad headspace, the best thing to do is get out of it as soon as possible. a lot of the time watching cartoons to distract myself helps, or having our gatekeeper kick me out of the front for a little while
it's hard to avoid impure regression cuz it just kinda happens sometimes but having positive experiences with regression can help make it less bad when it does happen. taking control of your regression is the first thing you should do - regress on your own terms, or age dream if you can't regress involuntarily. do things that make you feel small and happy. like for me, that's watching cartoons or playing with my stuffies! it also helps a lot to have a caregiver cuz they can make sure your regression is safe and pull you out if you're feeling uncomfy. it can also help to be around other age regressors when you're regressed, cuz that can help make you feel more small. it all varies depending on the person though! your little age could also effect that a lot, cuz a 2 year old is gonna have a way way different experience than an 8 year old.
but yeah! I hope this helps :D
-luna