https://www.youtube.com/watch?v=vVsXO9brK7M
1 who are you
2. what do you like to do
3. who do you do it for 
4. what they want or need
5. how to they change or transform as a result


In short, your life purpose is the contribution you give to other people, from your strenghts and from what you´re passionate about.


When I started watching this video I knew nothing about my life purpose, when I was done watching the whole video I still knew nothing about my life purpose.

Update: 1 year later and I've decided there really is no purpose to life. It's incredibly interesting to speculate on how humans came to be as I feel knowing the answer to that question would also explain our purpose (or lack thereof) but until I find the answer to that question I will hold onto my opinion about life having no purpose. 
I've also realized not having a purpose is not inherently depressing. In the same situation some people can be happy and some extremely sad. Which makes depression extremely scary because it shows that you do not need a tangible reason to be depressed and if something has no cause it has no clear solution either.
I have found a good way to move on with life in the meantime. Have a fun activity that you can do daily, for example playing csgo or whatever you genuinely enjoy doing (with friends if possible).  On top of that have one super fun and hard to achieve goal for example starting a tech company. This will keep you occupied from the everlasting string of questions and you will probably lead an interesting life, the scale of which depends entirely on you. Also stop caring about what anyone thinks of you, it will give your life a huge happiness boost instantaneously. 
当我开始看这段视频时，我对我的人生目标一无所知，当我看完整段视频后，我仍然对我的人生目标一无所知。

更新：1年后，我觉得生活真的没有意义。推测人类是如何形成的非常有趣，因为我觉得知道这个问题的答案也能解释我们的目的（或缺乏目的），但在找到这个问题的答案之前，我会坚持我关于生命没有目的的观点。

我也意识到没有目标并不是天生令人沮丧的。在同样的情况下，有些人会很快乐，有些人会非常悲伤。这让抑郁变得非常可怕，因为它表明你不需要一个有形的理由来抑郁，如果没有原因，也没有明确的解决办法。

在此期间，我找到了一个继续生活的好方法。有一个有趣的活动，你可以每天做，例如玩csgo或任何你真正喜欢做的事情（如果可能的话，和朋友一起）。除此之外，还有一个非常有趣且难以实现的目标，比如创办一家科技公司。这将使你远离一系列永恒的问题，你可能会过一种有趣的生活，其规模完全取决于你。也不要在意别人对你的看法，这会在瞬间给你的生活带来巨大的幸福感。