Unless you are training for a sporting event or are a sport professional you should be training for around 45-60min tops including a cardio warmup of 15-20 minutes.
Working out longer will just over-train your muscles and cause injury, remember we are trying to stretch the muscle for lean muscle mass and tear/regrow the muscle for building larger muscles. We should also only be training 1-2 core areas per session to allow the other areas to rest and repair (48-72hrs is optimum).
A session should look like this:
5 min: stretching
15 min: warm-up cardio
10 min: core area A
10 min: core area B
10 min: cool-down stretching
You should ideally have at least 1 cardio only day where you set yourself a distance or time related goal and each week try to beat it - e.g. 3km in under 40 minutes or farthest distance in 40 minutes etc.
The main focus should be that after your workout you feel a “little” bit sore but can still move without pain. When lifting weights the most important thing to worry about is the technique - lighter weights with good technique is better than heavy weights and bad technique. When you lift - exhale, when you lower - inhale and both movements should be controlled and slow for maximum effect - I try for 3/5 - 3 seconds up and 5 seconds down.