Complex sentence: The President of Honor of WWF in Spain used to be King Juan Carlos I, who was a known hunting enthusiast, practicing it from 1962, when with 24 years was invited by the German Baron Werner von Alvensleben to a hunt in Mozambique.
Split into simpler sentences: The President of Honor of WWF in Spain used to be King Juan Carlos I, who has been a known hunting enthusiast since 1962. In that year, when he was 24 years old, he was invited by the German Baron Werner von Alvensleben to a hunt in Mozambique.