Praise be to Allah, and may peace and blessings be upon the Messenger of Allah. To proceed:
There is nothing wrong with a person planning for the future, estimating what he needs, and hoping to achieve what benefits him in his religion and worldly life. He may say, “I will do such-and-such tomorrow, next week, or next year,” while attaching that intention to the will of Allah تعالى, saying: “If Allah wills.” Allah تعالى says: ﴿And never say of anything, ‘Indeed, I will do that tomorrow,’ except [when adding], ‘If Allah wills.’﴾ [Al-Kahf: 23–24].
Hope for the future is what motivates a person to work and build his life. The believer is commanded to take the necessary means while relying upon Allah and seeking His help. The Prophet ﷺ said: “Be keen on what benefits you, and seek help from Allah.” Narrated by Muslim.
As for being preoccupied with the possibility of death or with circumstances that might prevent a person from achieving his plans, to the point that this causes him to stop working and neglect his interests, this is not what is required. A person cannot live and work except with a certain degree of hope for what lies ahead.
However, the believer should not have excessive hopes in this worldly life or become attached to it. Rather, he should keep the Hereafter before his eyes. He should plan and strive for what benefits him, use Allah’s blessings to obey Him, and maintain a balance between taking the necessary means, relying upon Allah, and keeping his worldly hopes short.
And Allah تعالى knows best.