So I developed this little technique today when I was outside. It began to be cold, I had no jacket on because it was pretty hot at first. I envisioned a golden shield around me, (like you would in healing.) then I imagined the shield turning into flames in a split second and remaining so.
It felt pretty warm again, idk if it can prevent you getting sick but it makes you warm again.
This also an excellent exercise in element attunement. Nice work.
It’s a old book I read wicca wat depends u sign u say a word and the visual of fire surrender you.it was a 1999.book
Keep practicing! You will unlock and learn you things quite quickly!!! 
Maybe this knowledge wad granted to me by Lucifer unconsciously.
I use this too in the cold!.
people give me shit about freezing but i tell them “I’m not cold at all”
Well done, excellent effort, keep it up.