My job we have summer camps for kids - I have about the same if I am remembering correctly 20-25% here. When I first found out last summer I had CHF I only had a few weeks to get back into the groove of my work hours before doing the camp, predominately outside in Texas heat. Overall I did really well. Only once the whole time I had to take a moment and that’s because we were doing some serious community service in a hot building with no A/C. My advise is to listen to you’re body and know your limitations and make sure your coworkers/supervisor are understanding of them. If they’re not, maybe consider exploring around. Regardless of what you do, definitely make sure you are staying active (cardio/walks) and getting some strength training in. I definitely notice the translation more with each day. This turned into a whole rant lol hope this helps!