Why is Ganesha called ishta devata?

A deity “chosen” by a devotee for worship is known as an ishta devata. Some may be inspired by Shiva, others by Lord Krishna, according to sectarian leanings. Ganesha however, is identified as the embodiment of the Universe itself, one who contains all worlds within him. He is, in that sense, the Supreme One, and the primary ishta devata of all followers. Worship of Ganesha leads the devotee naturally and easily to all other deities.