Simplchaos and boyz4us, exercise was also a big question for me. I am going to write a longer post because I think it would have helped me when I started.... maybe there will be a few things that will help.
I had a great coach who encouraged me to do whatever I wanted (in regard to exercise) once I felt up for it. They said the first 3 weeks no exercise for sure (light walking ok) but after that would be OK based on my desire. My coach is also a nurse practitioner at my doctor's office, and the doctor supervised the whole thing, so I got a lot of really good medical advice. They weren't so married to protocol in the sense that if there was something to adjust for my particular circumstance they would, but I stuck pretty close to 100% (the adjustments were in adding IP packets or not for the most part). I have lost about 80 lbs on Ideal Protein over the last year, went through P2/P3 last month, and now have been in p4 for 2 weeks.
I have just seen
Kimo88 post a few times in another thread, but I think we have a kinship in similar stories to some extent, as my exercise experience was similar to what she describes above.
For me, this is what happened, and it worked well for me:
1. The first two months I had big losses and was only able to do walks, sometimes up to an hour, but this is much less than what I was doing before, which was a lot of hot yoga and heavy duty weights and cardio.
2. After that my weight loss slowed to 1 or 2 lbs a week, maybe 4 or 5 lbs a month. At that time I started to feel more energy, and just naturally wanted to do more - hiking more strenuously, swimming, hot yoga, etc. - this actually resulted in faster weight loss/inches, so it also didn't scare me.
I added in an extra bar or drink at that time, and again, it didn't slow weight loss. I only did it on the days I did something active. My coach actually said if I was going to do a lot I could add in a baked potato (plain) instead of the extra packet, but I never did that, as the extra packet seemed to work fine and something about the potato made me nervous, so I just trusted that instinct. Looking back on it I think it actually would have helped me. They had another (male) patient who was successful and lifted weights the whole time, and he did the potato.
Basically I did what I could while staying within protocol, with the option of the extra packet. If I exercised enough that I felt light headed at the end of the day, I knew I had pushed further than my body/organs etc. could handle with the amount of calories I was giving it, so I learned not to go that far. My body was very clear with me what I could and couldn't do, and I listened to it and trusted that. There was a like a wall that I would hit, it would clearly feel like "I'm done" and then I would stop. That would sometimes happen at night too - maybe I would be working around the house on something - cleaning or whatever - and then around 8:30 this "I'm done" feeling would come, and I would just trust that and lay down for the night.
I personally did not think I could do weights, as it sapped my energy too much, so I didn't. After a while my routine was hot yoga 3 to 5 times a week, 1 hour fast walk/hike on hills the other days.
I had a lot of energy to do all of this.
3. After about 8 months, I was about 15 lbs to goal, and started to feel very depleted and also about to start the holidays, and my weight loss had slowed to 2 to 3 lbs a month. My doctor said that adding some oil and fat sometimes actually helps speed weight loss at this point, and I did that. Per their suggestion, I added 2 tsp oil and actually some cheese here and there (about 1 0z per day) and sometimes an extra packet, and ate more red meat (higher fat) than I had been. My weight loss didn't increase any faster but I did keep losing weight slowly, and I think it helped me stay on program at a point where I started to get really bored with it. I was still able to exercise as I noted above.
4. After 10 months, I was about 5 to 7 lbs from goal, and started to feel extremely low energy. The doctor felt that perhaps my goal was too low, and I could stop if I wanted, but we decided together that mentally I just needed to see if there was any more weight to lose, so I had no regrets. Under their supervision and direction, I stopped all exercise for 30 days, cut out the extra ip packet and oil and did very few restricted foods. This made me miserable and I couldn't do anything but work for eight hours and go home and sit on my chair

.
5. After 3 weeks of that I called and said "this isn't working". They said there was a good chance that I would lose weight in P2 and p3, and we decided to start p2. That week didn't really help much with my energy (still was very depleted) because it's not that different from p1 to be honest, so after still feeling miserable for a week I called and asked if I could start p3 early, and they said because I likely waited too long to do p2 anyway, that it would be fine for me. I did lose 1 lb that week of p2.
6. After 3 days of p3 I had all my energy back and was able to go back to the workout routine easily, and felt strong. I lost 2 more lbs during p3.
7. I have been in p4 for 2 weeks and have lost another 1lb. For some reason I didn't gain the 3lbs glycogen, I'm not sure why, but I'm not going to worry about it

. I think it might be because I was able to go back to my workouts.
For me, keeping going with the exercise was really important for my overall well being, it helps my mental state tremendously, and also made me feel like I was keeping everything toned up and functioning - I wouldn't have wanted personally to not do that for a year. I think everyone is different. I think what did change for me, is I "unlinked" exercise from weight loss/control and began to see exercise for what it is - something to do for my health and strength, but unrelated to the loss itself. I.e. if I didn't work out I wasn't going to gain weight per say, but I just wasn't going to feel as good. I have a tendency toward compulsion when I get nervous about something, for example weight, so it was good for me to "unpattern" that part.
Hopefully this is helpful!
Good luck!
p.s. I'm 47 years old, and have been exercising most of my life, and actually eating relatively healthy with the occasional stress binge episodes or days - finally figured out the extent of my carb/insulin sensitivity by doing this diet - it's been a miracle for me. I had genuinely tried everything, and given it my best shot. I was always about 20 lbs overweight unless exercising heavily and very low calories/carbs, and then in my late 20s started a pattern of losing 10 lbs and gaining another 20 every year or so, until I was just very overweight and so diet fatigued I could hardly stand it, and my metabolism and hormones and pancreas and sleep/cortisol were basically shot to ****

. This was the first thing in 20 years that actually worked. I am able now on maintenance to eat foods that for 20 years would for sure have made me gain weight overnight in the past. For the first time it feels like my body is actually metabolizing and digesting the food properly and efficiently - before it just felt like it got stuck and weighed me down, no matter how healthy or how few calories... And now, the health aspect it just so calming and satisfying. I am truly so grateful. Now to focus on maintenance... the next challenge, willingly accepted

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Good luck!!!