In the AMC show, the Walking Dead, the main characters live their lives focused on every day survival. It is not really about believing in a brought future as much as it is about trying to make it from one day to the next.
Part of this is because of the situation that they are in which is fighting among the different groups and having to deal with flesh eating zombies all the time. They also have to deal with constantly losing loved ones many of whom they saw either eaten by or turned into zombies.
The combination of these things causes them to not have hope for any more than another day. This understandable and anyone would feel these exact same feelings if confronted with these circumstances.
But many people today live like characters in the Walking Dead without having their same circumstances. They live as if they may not see tomorrow and they are too shell-shocked to think about a future. You can see this in the food they eat, the way they do not get enough exercise or the way they do not get enough rest. Also many engage in substance abuse.
In order to have a great future you must take care of yourself now. If not, when you are older, you will be in physical trouble.
I am not saying that you have to completely end all of the bad vices, but you must manage them or they will steal your future. At that point you will really be like a character from the walking dead, but this time, a zombie.
Be good to yourself.