It is a general tendency for human to think about their future. When you have got so many scenarios in your head on how you intend your future to look like; on how smoothly, remarkably and memorable it should seem. When you probably want your future to look and feel wonderful as that of a person you admire.
Now, thinking things through can be a great thing of course. But being an overthinker can result to being a person that stands still in life. When you overthink or overanalyze too much about your future, the happiness that comes from doing things in the moment fades away. Your whole life tends to revlove in what I call "deceptive expectations". You must understand that our minds and thoughts are an insatiable dictators, it can never be satisfied with how much we feed it with our overly humongous scenarios. This scenarios can be both positive and negative scenarios.
Below are reasons why you shouldn't think too much about your future.

Overshadows your dreams
Like sailing on deserted waters, thinking too much about your future places you in the state of devastation. You must know that our imaginations are limitless and just somehow people over imagine the possibilities of what's gonna happen and start worrying over everything. When you think too much about your future, you create worries that weren't there before, making a big issue out of a problem that is so petite - a problem that just needs to be taken care of with a bit of consideration and attention; and simply overshadowing your dreams, hopes and plans with confusion. You overanalyze every possibilities of what could go wrong if you made a move.

Doing things above your capacity.
Everyone has something they are good at and able to do handily with splendid results. Thinking too much pushes you to do things above your capacity. And have it in mind that as you admire someone at something, you too have something in you that can be admired by someone too.

Comparing your future to another.
Everyone sees this world in a different perspective and with different lenses. Your own ideas could possibly not be what someone else would think on an issue and your achievements aren't built on following the path of another you should understand that. Thinking too much pushes you to the edge where you find yourself comparing just everything you do, everything you are to someone else's. You compare your growth, your achievements and even your flaws. You tend to use other people's success or victory as a benchmark to evaluate yourself and worth.

Engaging in too many things at a time.
There are always advantages of doing things at a time especially if you are best at one thing rather than juggling too many things at ones and never getting any of them done. That is exactly what thinking too about your future does, you engage in too many things at a time that you lose sight of the ones that are actually for you. You will find yourself not settling on one thing and obviously walking a wobbly line. Weeks, days and most of your life will be wasted just because you are trying to prove to yourself your life can be just as the one you perceive to be great.

Feeling of inadequacy.
I understand you probably want to be successful and be admired too or that you want your future to look like the scenarios cooked up in your head, and wish even if it is a little can become a reality. Thinking too much about your future poses you as an indeqency to yourself. And just as you are done comparing yourself, everytime you try your hardest to be similar to that big goals projected in your head, or everytime you want to measure up to the skills your colleague posses and you are unable to do so, you beat yourself up for not trying hard enough and that might even hinder you from trying again because you feel you aren't good enough for anything.

So you have read why you shouldn't think too much and worry about your future. I would advice that instead of thinking too much and creating problems that aren't suppose to be there, you should start by taking every decision slowly and at a time. Remember that all you do should be because you believe in yourself and not because you are trying to follow someone's path. You never know if you would pass it smoothly as that someone did.
Live in the moment and with every chance you have got to enjoy yourself take it but also be careful and know that all you do now have consequences and rewards in the future. Choose wisely.

Thank you for reading I will love to hear your own ideas and more reasons why and what thinking too much does to your future.