There are lots of reasons why people shouldn't be active or do highly intense activities. In my opinion, having a stoma is actually not one of them. Many people end up not doing things that they want to because they simply think they can't do it. Now if you have a medical reason not to do something then you should follow that reason. For the most part, whenever I talk to others who have a stoma they are actually rather active. There are simply a few people that have decided to shy away from the world due to their medical condition. I think that working out is a big part of not only my life but of many people's lives in the United States. Being able to move and lift weights is a great thing and with the correct planning and gear, it is possible for most people with an ostomy.
If you have just gotten a surgery then you need to heal. Healing and growing your abdominal muscles should be a process that you take slowly. There is a much greater chance of you having a hernia if you end up getting an ostomy. So this should be at the head of your thought process. Make sure to keep in touch with your medical provider and learn to get your body growing muscularly safely. It is important to not overdue a workout or a process and end up injuring yourself. It is not better to rush work out and hurt yourself than to simply take it slower and grow safely. I think it is very important to be safe and also to grow. This is all if you want to actually workout. I don't want to push anyone to get in shape if they don't want to. But if you were used to working out before your ostomy I want to give you hope in that you can still stay in shape after you are done with your surgery.
I think the best part of staying healthy is having great gear that allows you to do it without worrying about your stoma having issues. Ostomy gear is important. You want to find a bag setup and also a good belt to keep your ostomy bag from swaying back and forth while being active. It is a 100% personal quest to find the gear that works for you. This is a lot of trial and error, but you are not alone and there are tons of places to go and get good information. The first place should be your medical provider and also you can go ahead and talk to the supplier of your ostomy supplies. There are some amazing companies that are going to be a big help in giving information. These places do have a sales agenda but are usually willing to give good advice and free samples to back them up. I suggest you try it out and see what works best for you. I have had nothing but good experiences working through how to go hiking and backpacking with an ostomy. The advice I have gotten was mostly great and a few things didn't work at all. So I suggest you try the gear close to home and in the safety of your neighborhood. This worked really well for me and I think that is a great way to start.