13 years now. I first considered it when I was 12 after my dad said he didn't care if I died or became a drugged up, homeless hooker (yes, that's what he said!). I don't know how I'm supposed to keep going until my parents die, but that's the plan. My dad will probably be the first to go when it's actually my mom I care the most about hurting, but oh well.
I keep playing that game people play with hourly work where you break up time periods into shorter chunks - e.g. I don't have an hour left until quitting time, just 4 15 minute intervals. With years, I make it even more abstract. The last three years, when I was in grad school, flew by faster than any others. So, instead of 10 years in the future, I think "3 grad schools plus 1 year". Makes me feel like I have less time to wait.
Every time I've felt despair, I just tell myself it will soon be over. The 10 years between 15 and 25 felt like nothing. What's another 10 when they'll undoubtedly go by even faster?
I have no previous attempts. Too much of a pussy, I guess. I tell myself it's about my family, but I'm probably just a coward. I really need to buy a gun soon before any hard gun control is legislated. That's my preferred method. Everything else sounds too long and difficult.