As someone who had depression for quite a while and basically wasted 5+ years of his life due to that, at least from my own experience I can definitely say that

As someone who had depression for quite a while and basically wasted 5+ years of his life due to that, at least from my own experience I can definitely say that there would have been ways to prevent this depression which could've given me 5 productive years back. During this time I wasn't working or doing anything productive.