Generate an overlapping word between the given two sentences. When you find the overlapping words, they don't have to match exactly, e.g., "survival" and "survive" are valid overlapping words. Little words like "the" or "of" don't count! You must generate significant words which are not the stop words.

Sentence1: healing requires rest. 
Sentence2: Healing and cell regeneration follows.
healing

Sentence1: creating paper requires cutting down trees. 
Sentence2: Rainforests are destroyed by logging and all of the trees are cut down.
cutting

Sentence1: When an animal moves, it burns energy. 
Sentence2: Burning energy is what allows for movement in animals.

burns