Do you need Training or Diet Help??? Let me know!

I'm setting a goal of losing 30lbs. Im currently 140 lbs at 4"11ft. I've been browsing through some workout routine on the internet and found "30 day shred" and followed it through YouTube this morning. I used to go to the gym and had a personal trainer and this 30 day shred was almost the same routine as what he'd give me. It has been months 3 months since i last went to the gym and i gained 6lbs since then. Going back to the routine, it has 3 or 4 levels and im currently on the first one, meaning the easiest. It has 3 circuits consisting of cardio like jumping jacks and some more jumping then some push ups and squats and lunges and so on. The routine lasts for about 20mins but i didn't make it for more than 10mins. I stopped on the first circuit and missed the two because i started to feel dizzy and nauseous.
I know that it's not gonna be easy and im not in a hurry to lose weight . I want to lose it the healthy way this time and not by starving myself off ,also i want to give my skin some time to recover because it tends to sag when i lose weight fast.
Is it okay to push through even when feeling dizzy or do you have any tips on how to avoid feeling dizzy while working out.