My Knees!!! I can't stop now.......

Treadmills can be bad for knees because of the surface. 140 min a day of working out is also a bit too much. 80 min on a treadmill (idk if you are running or walking) is a bit too much unless you are training for a race. For strength training I'd go recheck your form on things like lunges and squats if you are doing those. If you do those wrong continuously then you will hurt your knees. I did squats and lunges wrong for years and finally fixed my form and my knee pain went away (keep the knee behind the toes when bending the leg, mirrors help ).
Yes, switch up your cardio options. The stationary bike is a good one if you are able to get on one, it's less stress on the joints and a good alternative to running/walking if you are injured.

Can you check out swimming options? It would be a lot kinder to your knees and can be very aerobic since your arms are probably not used to doing as much work as swimming involves. I walk a lot and swimming really challenges me. Even water-walking in the pool.

Not knowing what kind of strength regimen you are on it's hard to say but make sure you are giving breaks on that for the recovery time.

Honestly, it sounds like overuse symptoms. That is a lot of work in a week, coupled with the weight loss... your body is adjusting and you have to give it time. Remember, your stressing the body to strengthen up in all areas while under a restricted diet. Too much and something will break.

That being said, depending on where it hurts you may need to change it up a little.

You mentioned knees... where at on them?

Any other pain (even if you think it's "good" pain) like on the soles of the feet, etc?

It sounds like just overuse. That's a good thing, it will go away on its own.

Find some time to take 5-7 days off. I know you said you don't want to but it will help. Just watch your nutrition and intake close. Eat some extra, just not junk. Good protein, carbs, etc. Up the intake a couple hundred calories above your maintenance level. It's only a few days, your metabolism is already high. It shouldn't affect you much if at all.

You will feel a lot better, then start back up slow.

Remember strength training breaks down tissue very well, doing that much stuff combined with not enough calories starts to add up.

If you really must workout, try some light swimming with good form. Kicking "loose" while swimming will aggravate the knee.

Your body just needs to catch up a bit, if you don't let it though... It'll end up with rehab that takes a lot longer.

I have been doing awesome. I work out 6 days a week up to about 140 minutes a day, one day rest, which I hate. Treadmill 80 minutes and/or Strength & kickboxing. I started out just a half hour a day August 20, 2012, total weight loss 58lbs. However, now my knees are in serious pain. Has this happen to anyone else? The nurse at my job stated I need to only work out every other day. I am freaking out, I feel as though I should be getting stronger and going harder and that’s what's I been doing. I guess I been going too hard. Will this slow down my weight loss progress? She also stated that I must slow down on the treadmill and another co-worker who is a little fitness guru suggested I just switch it up to like aerobics or yoga. I don't want to really get injured and have to stop all together. Any suggestions.......thanks in advance.

It DOES sound like maybe you need to slow down a little to let your knees recover. What if every other day you cut your speed and everything down by 25%? When I have had issues with my legs, but don't want to cut my DAYS down, I have done days where I do a slower pace with a lower incline.