I fly about 105 times a year (I mean, 105 "legs", not 105 roundtrips), and have been doing so for the past 7.5 years. I would say AMA, but... Not joking... I am taking a flight in 2 hours. SFO to JFK.
I don't say this to beat my chest. Traveling for work, like this, is terrible in the long term. I wish there was a better way.
I've been at the 100k-mile tier with US Airways (and now American Airlines, courtesy of the merger) the past two years in a row. Thankfully, this year I'm dropping down below that; I'll probably clock in around 60-70 thousand miles flown in 2015, depending on how much I do in the final quarter of the year.
On one hand, it's much more relaxing to not be constantly away from home and shuffling between hotels and airports. On the other hand, I'm going to miss the perks; might have to switch over to Delta for next year, since AA only provides free upgrades at the very top tier.
I tried many things. In essence, I try to eat healthy, and exercise in moderation. The biggest though is trying to sleep properly as much as possible.
I found that when traveling too heavy for too long, it's hard to do any of these three things above.
