A) When you're completely on top of life, happy, smooth-sailing with all the stars aligned?
2) When things don't go your way, you're in the middle of adversity, life is down on you, but you pick up and you are walking, you're not on top of the world but you're pretty close. When you're happy despite your non-happy circumstances (not unhappy) and you look forward to the great things that you have and the even greater things you're working towards.
Just thinking about this. It's like the 10 mile run I went on today. If I didn't go running today my body would feel relatively no pain. Instead, I did go running and I'm in a little bit of pain....that pain is uncomfortable (and gave me a really good excuse to spend my holiday afternoon in the hot tub), but I ran 10 miles. It hurts, but I'm 3 miles away from my 1/2 marathon and 15ish lbs (I've lost 40ish so far) away from my goal weight.
Life is great when it goes your way. Don't get me wrong, it's awesome. And then sometimes life is an everyday battle or an uphill climb for 8 miles in the sun (no pain, no gain!!!) You barely make it through, but every challenge makes you stronger. And then sometimes you're running along and you hit a hill and you gather up some courage, take it by storm and sprint up the damn thing. (Ask my roommate in college, it's one of my favorite pastimes....especially at the end of a run, can't help myself.)
I think it's better...to be dead tired and sprint up that hill than to be running easy on a slight downhill slope. We all enjoy our moments of bliss. But, as for me, I'm gonna allow myself to feel great even when life could dictate otherwise. In some sort of mathematical equation of joy-pain*(mental attitude/life circumstance)=happiness, I think you're somehow happier in the latter, though it may not feel that way. Pat yourself on the back or have a private dance party in your room in celebration of your hard-earned, seemingly mediocre life. You deserve it...more than the smooth-sailers. And next time we hit a hill, try not to cough in my dust.