1. Warm up properly. It seems excruciatingly long warm up routines are all the rage these days. Simple solution - gradually get your heart rate up (we like the rower), if you need mobility work - do it. It should not take longer than 10 minutes to get ready to roll though. If you need that much mobility/flexibility work than schedule it on an off day and devote a full session of gym time to it.
2. Sprint. For most, long distance time consuming "cardio" is well.....a waste of time. Sprint for maximal fat loss, sprint for conditioning purposes, sprint for power and strength development. Start with a 1:1 or 1:2 work to rest ratio and be conservative with the sets/volume in the beginning.
3. Carries. Pick up something heavy, db's or kb's, and carry it for a distance....fast. Carries are great for your core, grip and posterior chain, not to mention overall conditioning. Examples include farmers walks, waiter's walks, front rack carries, etc. etc. Put these at the end of a training session for a great "finisher."
Incorporating any (or all) of these tips will help you regardless of goal. Stay thirsty....I mean simple, my friends!