According to Qohelet (Ecclesiastes), the ideal life is not to seek the mere future or gain an immortal life elsewhere. Rather, it is in the here and now. Tomorrow is not in our hands. The world is an uncertain one (Eccl 11:1-6). Heaven and earth are fair to everyone (Matt 5:45; Dao De Jing 5: 天地不仁). Anything can happen anytime to anyone. That reality is not simply because this world is evil but because the nature of life in the world involves vulnerability and death. We are hebel ("vapor, breath" in Eccl 1:2; 12:8). We must say: "I live short and I am breath or vapor." Of course, this reality with "hebel" does not implicate or suggest a life of living carelessly or irresponsibly. Hebel or short-lived life does not mean that our life is worthless or vain. If you think that way, your reading of Ecclesiastes is misleading.
Rather, ironically, our short life is more valuable and precious than otherwise because we live short. So, the right attitude is to remember our death and value our time so preciously.
Focus on your valuable life to be happy, enjoy your life in a good way (Eccl 3:12), work with others (Eccl 4:7-12), and love them as you care for yourself. "I know that there is nothing better for them than to be happy and enjoy themselves as long as they live" (Eccl 3:12). You need to follow what your heart tells you, not being pressured by others (Eccl 11:9).
So, the wise person values today and now, remembering his/her eventual death (Eccl 7:2, 4). "It is better to go to the house of mourning than to go to the house of feasting" (Eccl 7:2). "The heart of the wise is in the house of mourning; but the heart of fools is in the house of mirth" (Eccl 7:4).
Conclusion: So, save time (Eccl 12:1-7). Memento mori: Remember that you die. Carpe diem: Seize today. Amor fati: Love of fate.