Complex sentence: Even after his friendship with Kamina, he continued to act cowardly and to doubt his own abilities, but Kamina's inspirational speeches would give him just enough confidence to endure the fear and accomplish something.
Split into simpler sentences: Even after his friendship with Kamina, he continued to act cowardly and doubted his own abilities. However, Kamina's inspirational speeches would give Simon just enough confidence to endure his own fears and to accomplish something.