New to the exercise world

[peekawho]

Since losing almost 45 pounds, I've joined a gym and am now trying to increase my cardiovascular fitness.  I had a scare last year with a tentative finding of pulmonary hypertension, which has yet not been proved nor ruled out.  However, since losing all the weight, I'm no longer having shortness of breath when I exercise.

Anyway, I can't seem to increase my endurance on the elliptical.  20 min is the most I can do, and I'm dying after that.  My heart rate gets up to about 140-150, but I'm on meds so it doesn't get much higher (I also had problems with unexplained tachycardia, hence the meds)

I'll go back to the cardiologist eventually, but anyone have any ideas?  I go to the gym about 3 times a week, cardio every time, water aerobics once a week, and weight training every time.

Thank you in advance, and good to see everyone.  Some of you I know (big surprise, eh?) some I don't.  

[Dr_Aparna]

You need not just hit the gym to exercise.Try and incorporate other forms like walking or slow jogging outdoors.
Once you have reached the limit that you can-20 mins on the elliptical- there is no point in pushing yourself beyond that.
Also you need to consider your medical condition.
Do weight training 3 times a week and some form of cardio everyday for 30-40 mins.
Dis continue if you feel any shortness of breath.
Endurance is built over time with consistency in your routine rather than overdoing it when ever you exercise.

[peekawho]

Weight watchers, and 6 months.  I'm still slowly trending down, but its mostly due to the exercise now.  

I did not exercise at all during those 6 months.  I waited til I got to goal.  

[itsallwaves]

How did you lose the 45 pounds and how long did it take?