i'm unfit because of not being able to do stuff because of medication... I just thought a plan would make an even balance of muscle,
In that case consult your doctor. The medical centre I go to has dieticians and a couple of doctors with sports backgrounds which makes things a heap easier. Having a doctor that understands what you want to do makes a huge difference, some people just don't get sports.
And seriously, plans are pointless unless you are already quick and strong. There is method to my madness, if you do stuff when you feel like it then you are-
1. More likely to stay interested as you aren't being forced to do things you may not feel like. Motivation is a hard one, the more fun you have the more you'll do.
2. Less likely to get injured. If you are feeling shot then you'll just take time off.
3. Your sessions will be of better quality.
The last one is the most import out of those. For one you'll actually want to do the sessions so you'll put everything you have into the sessions you do. Sometimes if you are made to do a session when you aren't quite ready for it then you'll show up, go through the motions for no real gain. Add to that the longer recovery that inevitably follows and it's a compounding problem.
In your case there are other issues which you'll need to talk to a professional about.
If you are wondering how far this 'do what you feel like when you feel' regime will take you, well, I ran my first sub 30 minute 10km and my first sub 2 hour Olympic distance Triathlon with no real plan. I just did stuff when I felt like it. There was still about 20hrs on average per week of work but I had no 'plan' as such.