Manifesting in this department can be a cop out. Can being the operative word here.
Don't think you can skip the work with the magical sorcery of LOA. Health takes effort. Start with cutting the processed shit out of your diet. Eat whole food. It isn't hard, but being consistent, just like with most other projects, is.
Exercise. Lift weights, ride, swim, or run. Yoga and other low output disciplines can be added later.
Buy a water filter or a Brita jug if that's too expensive for now.
Breathe. Spend time focusing on the air you intake. Big breaths. Wim Hof method is good for this and ties into LOA.
Get sun. 20 mins/day of as much exposure as is legally possible is a good start.
Buy basic supplements. Zinc. Magnesium. Vitamin D. Probiotic. As high quality as you can afford.
Ok cool. You've been doing this for a couple months now, and you're consistent and are in the habit of living a healthy lifestyle. By this stage you probably look better, definitely move better, and definitely feel better.
LOA is starting to take effect. You spend time thinking and putting effort into this area of your life. Think of fitness as a planet made of LOA. The larger and more important you make this area of your life, the more it starts to affect the other planets and moons in the system. People treat you differently because you look better. This is an amoral fact. You start to get more opportunities in the area of fitness/health, as well as your fitness/health bringing more opportunities in other areas of your life like your work and your dating life.
This further encourages you to put more effort in, which the further improves your life.
There is also the affects of positive, mindful affirmations that can be of massive benefit. Like deciding that you don't get sick anymore. I don't have a heap of experience, as I'm just starting down that road, but I've heard great things come of those affirmations. Have a look into it.
I've never felt better, nor had more opportunities arise in my life in multiple arenas, then when I have been consistent with my health and my fitness.
Give it a shot.
tldr; don't skip the work.