Nevertheless, Johnson is required to prove a causal connection between his injuries and the June 15, 2014 incident. Wal–Mart Stores, Inc. v. VanWagner , 337 Ark. 443, 447, 990 S.W.2d 522, 524–25 (1999). In many cases, the principal evidence of causation for a claimant's injury consists of the claimant's own testimony.