I guess a hot pepper in my butt will make me extremely
hot and bothered 
But there's still no guarantee of hardness! Don't know about wasabi though... the kind one finds in a restaurant isn't very potent.
Both
FortunateOne and
mcloving76 agree that as soon as there is an erection, go at it immediately and don't let it go away. This is very true for me as I find once the first erection is gone, it takes too long a time for the later ones, which are a lot softer, to appear. I always ask for some kind of massage at first no matter what; I have also had one massage session with Katlyn, who gave me a great and relaxing massage, but the release at the end was not possible because an erection had already happened 15 minutes ago. I'll visit her again and see if we can fix that problem
To answer
sevenofnine's questions, if I do it myself, it varies between 3 - 10 minutes. A good BJ may take 5 - 10 minutes. But it's possible for BJ and HJ to have no effect at all when I am in the 'no hardness for me' state. Penetration sex, when stars align and make it happen, also takes around 5 - 10 minutes.
dood, I am relatively healthy I think. I think the problem is mental, which somehow also affects the physical. I don't think I have DIY'ed to a Playboy Centerfold, but I think there is truth in the gap between fantasy and real girls. Also, all the sexualized imagery in the media most certainly doesn't help.
And... what? Intelligent people have a harder time having sex without commitment? It probably just means that 'I' don't know when to shut up to just enjoy a good romp in the sack (on a bench, or wherever) goddamit! I know I will stay single forever... I am not a commitment-type person as the concept of a life mate makes no sense to me. Even if a person is perfect, which is impossible, there is still only so much one could learn from each other. The more, the better (within reason)! On the other hand, I could learn to commit to my favourite SPs

(I'm still in the discovery & evaluation stage)
A brief summary of the generous contributions so far is as follows

:
No's:
- sleep deprivation produces foggy mind state not conducive to pretty much any task
- stress makes it hard to be hard. This is probably why 'morning wood' is at maximum size and hardness because the mind and body are both relaxed
Yes's:
- some food, but not too much. I also remember from reading the Chinese farmers' almanac that 'no food shall be eaten an hour before sex'.
- some degree of exercise to improve blood circulation
- practice makes perfect, although it's more valid to say 'perfect practice makes perfect'
- varying between booking in advance and with a short notice
- watching erotic materials or thinking erotic thoughts prior to visiting SPs
Conflicting views:
- masturbation: 'if you don't use it, you'll lose it' or 'abstain for a few days before sex'