Life is unpredictable and our lives rarely turn out exactly like we had planned to. That is what happens when you have just decided to lose weight or join a gym and you find out you are pregnant.
During your pregnancy you need to take it easy to make sure you and the baby are healthy and safe. But healthy and safe doesn't mean that you are supposed to be eating for two and rest all day long. Exercise is a part of making sure you and the baby stays healthy. You need to be strong for the delivery and so does your baby.
By continuing with your exercise program you will still stay in shape. However your program needs to suit your pregnant body and not the body you had before you had a growing baby inside. That is why it is good to seek out a personal trainer who specializes in pregnancy, called pre/post natal specialization. If you are new to exercise start small and build up your strength. By small I mean 10-30 minutes depending on your fitness level.
Walking is an excellent way to exercise , pregnant or not. It is an easy form of exercise that anyone can do. You really have no reason to use your pregnancy as an excuse not to exercise. As much as it is advised to exercise this does depend on how your pregnancy is going and there might be times you are advised not to exercise. Make sure you talk to your doctor and and do not exercise if you are not feeling well.
Eating for two isn't necessary as long as you have a balanced diet. Your midwife should be able to give you information about what foods to avoid and what to eat.
Don't use pregnancy as an excuse not to exercise, see it as an opportunity to become a healthy strong mom. You will definitely need it once the baby is here.