Valid is similar to Legitimate. Legitimate is a synonym of Just. Just is a synonym of Reasonable. Reasonable is etymologically related to Able. 
Anxiety is a type of Emotion. Emotion can be Pleasant. 
Valid <--SimilarTo--> Legitimate <--Synonym--> Just <--Synonym--> Reasonable --EtymologicallyRelatedTo--> Able 
Anxiety --IsA--> Emotion --HasProperty--> Pleasant 