You need to fuel the body correctly protein shakes are good but you need to ideally look at consuming 2 litres of water a day this will prevent de-hydration and provide your muscles/body with good fuel and also help your body with recovery
Eating Bananas is very good , consume one around 15-20 minutes before training these contain a really good level of natural energy ,
It really is dependant on wether your aiming to get fit or get massive , there is so many things you can do to increase muscle
Press ups - heaves 'chin ups' - sit ups - bench presses - swimming is a great way of getting fit and also increasing stamina
try to run on natural ground rather than tredmills , firstly it does most of it for you , and seconedly gets a bit boring ,
set your self goals! just because harry lifts 3000000 kg weight doesnt mean you have to compete , start at 5 and do a million if you can comftabaly then the following week do 10 kg etc etc
stick to it give it time and within 2-3 months you will really start to feel the benefits
Rest days are vital depending on where your going or how far you going with your GYM work look at doing 3 days a week for now then move into a 5 days routine then use the weekend as a bit of R/R
It takes weeks to get fit and build muscle but only days to loose it ! Good luck matey
PS.. muscle strain allow a week for reco, then into light sessions ,