Question: When asking around, I've never heard anyone agree that a young, healthy person should end their life by suicide. But I also don't know what reason there is for that consensus. 

Did Buddha teach anything regarding what makes life worth living?

Answer: 
You shouldn't even think about things like suicide. Thoughts will be full of negative emotions and states that it will drag you to lower planes. 

When you are doing the act you will have negative thoughts which would mean that your next life is bad.

You are also breaking the precept of not killing which is very grave. 

Also it is best you see a doctor but until then practice Metta to your self and others.
The [sutta](http://www.sacred-texts.com/bud/bits/bits077.htm) doesn't say that the Buddha allowed him to commit suicide. When Mara reported this to the Buddha, venerable Godhika committed suicide. Then the Buddha saw what has happened and said that he has attained Nibbana. 

According to Bhikkhu Vinaya, the only allowable act that comes close to committing suicide is rejecting medication, if you are suffering from a terminal illness and being a burden to everyone around you.