Ariel Merari, a psychologist who fought in the Arab-Israeli war of 1973 and has spent the past three decades studying the attitudes of terrorists. Some of his most notable work is on Palestinian suicide bombers. He has spoken to friends and families of suicide bombers, and even to would-be attackers who failed to detonate their explosive belts before being captured.
His first conclusion is that Palestinian suicide bombers are usually not suicidal. They aren't depressed, or otherwise mentally ill, nor do they tend to be drug or alcohol abusers. What's more, these supposed Islamic warriors aren't especially religious. By and large, they didn't suggest religion as their primary motivation, nor was there much hope of a glorious afterlife.