The fact that property may be utilized more profitably, should a variance be granted, may not be considered grounds for a variance. In granting a variance, the Board may attach to it such conditions regarding the location, character, or other features of the proposed building, structure or use as the Board may consider advisable to protect established property values in the surrounding area, or to promote the public health, safety, or general welfare. Failure to begin or complete an action for which a variance is granted within the time limit specified as a condition of the variance shall void the variance.