Kara at Mama Sweat posts her favorite one-hour gym workout, involving 30 minutes on the stationary bike, 20 minutes on the treadmill, and 10 minutes in the pool: a mini-triathlon. It sounds pretty good, and has the advantage of being simple and easy to remember.
I was pretty fixated on the idea that because of time to change/shower, I had to either swim or run at the gym. Not both.
Then I recently started doing some running drills that only took up 20 minutes, and part of the drill was to keep the running short, so I tried "jumping in the pool for a quick swim." I found out something important: It doesn't actually take all that much extra time to change for a brief swim, if you were going to shower anyway. And if you love swimming, it feels really good.
So now I'm one of those crazy gym people who heads all sweaty into the locker room, puts on a suit, and heads right back out again for "workout number two." (Sure, workout number two is only ten minutes, but still.)
One little thing to add though. I think the act of calling something a "one hour" workout sets up a mental block of sorts. I know that some people will look at this and say "I don't have an hour" or "I have an hour, but it's really only 45 minutes because I have to change and shower in my hour." And then they will skip right over it, looking for a "great 45-minute workout."
But of course, any "one-hour" workout (including this one) can be shortened if necessary. It's just like cutting back on a recipe: divide all the ingredients by whatever amount you need to cut back. Round to the nearest minute, and you're good.
So, for instance, Kara's 30-20-10 workout can become 22-15-8. Voila. A forty-five minute workout. And it's just as "great" as the one-hour workout she posted.
I know it may SEEM obvious, but it's almost as if sometimes you feel like you need "permission" to tweak someone else's "perfect one-hour workout." It took me a while as a novice exerciser to realize I could do this.