Systems in nature tend to undergo changes that result in

Higher entropy

Explanation:

Entropy is a measure of the disorder in the system and in nature, systems favor a state of greater randomness or disorder and hence a higher entropy

In nature, systems tend to go from a higher energy state to a lower energy state

Reactions are always spontaneous if they are exothermic and go toward a higher entropy (in exothermic heat is released)

Reactions are never spontaneous if they are endothermic and go towards a lower entropy (in endothermic heat is absorbed)