We live in this world according to our life span but we never know when this life may come to an end. Youth is a fleeting experience and with the passage of time it turns into old age. One cannot even be sure about the ease in this life. Any time one may land into hardships. In short, nothing is constant in this world.
In Jannah, however, everything will be permanent. Life will be without any danger of death, there will be health without any risk of disease. There will be happiness and bliss without any fear of aging. Everywhere there will be happiness, ease, comfort, enjoyment without any pain, worry, hardship or distress.