Prior to my pregnancy, I was a bit of an exercise nut. Before you start to hate me, let me reassure you that I do not, for the most part, enjoy exercise. I will not be telling you about how incredible you’ll feel when you can bust out fifty push-ups, or the elusive endorphin rush you’ll get from running ten miles. (I’m pretty sure that’s a myth propagated by Nike, anyway.)

But I hate looking and feeling fat and tired and gross even more than I hate exercise (which does not bode well for later on in my pregnancy, I know). So before I got pregnant, I would try to run a 5K three times a week, go for a swim, take a yoga class, and do strength training twice a week. The key word here is ‘try’ – there were many weeks when I did about half that.

So how does my exercise schedule change now that I’m pregnant? Here’s a quick guide to maintaining or creating a regimen of exercise during the first trimester.

If you were an intense exerciser…
You may want to take things down a notch. Sure, you can be like this lady, who ran the Boston Marathon when she was 36 weeks pregnant, or this CrossFitter who is still lifting weights just weeks before her baby’s due date. But you don’t want to overexert yourself, especially in the first trimester. Scale back on your exercise a bit, and just take it easy for a few months. I’m not saying you should stop entirely, but now is not the time to put unnecessary stress on your body.

If you were a moderate exerciser…
Keep on keepin’ on! Talk with your health care provider about your exercise regimen, and ask what he or she recommends. You may want to modify certain parts of your routine to accommodate your little passenger. Pregnant women produce a hormone called relaxin, which helps to lubricate the joints. Because your joints are looser, you can be more prone to injury. I’ve been experiencing a lot of knee pain lately, so I’m increasing my swims and decreasing my runs.

If you were a couch potato…
It’s not the time to start training for a triathlon, but you should get up and move every day. Try to squeeze in at least 30 minutes of gentle exercise, even if you’re just taking a walk around the block. If you’ve never been active, it can be hard to motivate yourself, but you’ve got a brand new reason to get your butt in gear!

The First Trimester
This is the time to get your exercise in. Studies have shown that women who exercise early on in pregnancy report fewer uncomfortable symptoms in the second and third trimester. Another study found that women who continued their pre-pregnancy exercise regimens gained less weight later in their pregnancies than those who stopped exercising. In your second and third trimester, your balance will be affected by that burgeoning baby bump, and certain activities will get a little bit more difficult, so the time to start is now!

What Are the Risks?
To safely exercise during the first trimester, you’ll want to stay hydrated and keep your heart rate down. Experts used to recommend staying under 140 beats per minute, but today’s rules are less exact. Drink lots of water, especially if it’s warm out. Pregnant women should already be drinking at least ten cups of water a day, and you should drink even more if you exercise. If it’s too hot out, skip your workout. Overheating is dangerous for you and your baby, especially in the first trimester.

What Kind of Exercise Should I Do?
You can do almost any kind of exercise during your first trimester, within reason. Use common sense here. Tackle football, learning to figure skate, skiing, and other activities where you could fall or be injured should be avoided. Most health care providers don’t recommend horseback riding, since the jostling can cause placental abruption and even experienced riders get thrown sometimes.

Stick to safer activities that don’t put as much stress on your body. Swimming is the perfect exercise for pregnant women in any trimester. If you don’t feel like getting your gear on and going to the pool, just take a brisk walk or jog. The important thing is that you’re keeping your body moving and your blood flowing. It’s good for you and the baby!