I found this post at DiscoverSikhi.com by "Akal Purakh Di Fauj":
The point of Simran is not to achieve Ridh-Sidhi powers, even possessing them. We are taught they are nothing but a distraction - 'a cheap way of fooling people' as Guru tegh Bahadur ji said to the executioners.
Once Guru jee was travelling in a boat across a river and the Sikhs waited on the other side. A yogi decided to show his power and walked across the river. When the Guru arrived on the opposite bank, the yogi claimed that he had much more kamai than the Guru. The boatsman did not want to take any money but the Guru insisted on paying him the full amount - two paisas. The Guru asked the yogi how many years it had taken him to achieve the skill of walking on water. "14 years of in-depth samadhi and simran," replied the yogi. "Well," said the Guru, "now you know that the 14 years of kamai (spiritual earning) has been worth 2 paisas."