Im 23 weeks and my doc says its fine as long as you continue the same level of avtivity that u were doing pre pregnancy. I did a lot of weight training prior to being pregnant and my husband and i have been going to the gym and running since the beginning of my pregnancy and this our first child. Just listen to your body, stay well hydrated, and try not to lift anything over 20-30lbs to avoid getting a hernia since your abdominal muscles are weaker now. Good luck!
Yes. Walking is really treat, squats, jogging(talk to your doctor first), swimming, exercise ball, small weights, hiking. Just make sure to stay well hydrated and If you ever feel tired or out of breath take a break never push yourself.