I think the convicted can answer this question better than I. They almost always prefer to keep living.

It'd be interesting to see numbers on how many people serving a life sentence would choose to commit suicide if materials for a painless suicide were readily available. Prisons actively attempt to keep people from doing so, and it's apparently frequent enough to be a major problem at some prisons.

Depression can be a factor here.

I think depression comes with the punishment of life imprisonment, so the ? about the availability of suicide is still valid.

> How is execution different than 150 years in prison

In China, it's much cheaper.