Is there a means in Islam that a Muslim can do or say to enter Paradise whenever he wishes, excluding martyrdom in battle?

Entering Paradise is not achieved by wishful thinking, but by righteous deeds and by the grace and mercy of Allah. "And that is Paradise, which you have inherited for what you used to do." (43:72) Paradise is Allah's most precious commodity. A Muslim cannot transfer to Paradise whenever he wishes, because departing from this world is not by his will, and because he cannot be certain that he is among the people of Paradise, for outcomes are in Allah's hands. Indeed, a person may perform the deeds of the people of Paradise or Hell, but the decree has preceded him.