"I’m not going to lie. Working out sucks," she told the June issue. "Which is why I love taking classes, because I’m surrounded by other people and that keeps me motivated and accountable."
The 34-year-old actress-turned-entrepreneur said she likes to mix up her workout.
If she only has 30 minutes, Alba said, "I'll do a series of burpees, mountain climbers, squat jumps, planks, and a few sun salutations."
Alba's road to fitness began more than a decade ago, while filming the "Dark Angel" series.
"I attribute my athletic body to the martial arts, gymnastics, dance, and strength training I did while filming 'Dark Angel,'" she told Shape. "That’s made me strong and really set the bar."
But it wasn't until having her children that she felt comfortable with her body.
"I wasn’t truly confident about my body until I had my daughters, Honor, 7, and Haven, 3. I felt more comfortable in my own skin after they were born," she said. "Plus, if I want them to be happy with their bodies, I need to walk the walk."
But this active mom and Honest Company founder has also found ways to be still.
"When I need to zone out and quiet my mind, I listen to a meditation podcast from the UCLA Mindful Awareness Research Center [marc.ucla.edu]," she said. "Each one is literally just three minutes long, so I can go into a bathroom stall or do it in my car. But I’m really intrigued by Transcendental Meditation. Everyone I know who does TM has this inner peace and a glow. I want that."