Choose the correct preposition

1. How do you manage to keep
   [in|to] such good shape?
2. Drinking too little water can lead
   [to|in] headaches.
3. Don't put any milk in Jason's coffee; he's allergic
   [from|to] all dairy products.
4. Samantha still hasn't recovered
   [in|from] her bad cold.
5. It is important to use sunblock on your skin to protect it
   [from|to] sunburn.