Combining strength and conditioning is something I've been struggling with since I started training at age 13. And combining strength and conditioning work has been a giant part of my coaching life - from UK to London High School. Below are some notes on what I've seen work on myself and others. Many of these things are going to be unpopular and a blow to your ego. GET OVER IT. There is a giant chasm between the internet and the real world - and this includes training. So understand that what you see written about on social media (or a supposed "real" video) isn't going to be real life.
Also, if YOUR experiences differ from mine, I have zero problem with that. That doesn't mean you are wrong or I am wrong - it just means that your personal experience was different. Note that "conditioning" means being in bad-ass, kick-your-opponent-in-the-garbanzo-beans shape. However, if you are very overweight/out-of-shape/long history of doing nothing - the same rules below apply.
1. If you are in horrid shape now, your lifting is going to take a giant dump. GET OVER IT.
2. If your job is a police officer, firemen, armed forces - and you struggle with chasing barbell numbers and are sacrificing recovery/conditioning - GET OVER IT. Your job performance is more important (I get this question all the time.)
3. Main Lifts - Your lower body volume should be LOW. For younger athletes - no more than 2 lower body main lifts/week. For older athletes, 1 time/week. THIS IS LONG TERM SUSTAINABLE. I have zero interest in the 6-8 Week Crue.
4. Lower your TM (training max)- the lower we train, the stronger we get with fewer to no plateaus.
5. Do not chase numbers - chase performance. Remember that you aren't supposed to feel like dook after each workout.
6. Lifting - 2-3 times/week. Conditioning - 2-4 times/week. How you divide that up, is up to you and however it fits into your life. Don't wait for perfect.
7. If you want more lower body volume - reach into the assistance pool.
8. Learn how to train harder, quicker. If you can't do 3 movements and kick ass, you aren't doing those 3 movements hard enough. This is not contradictory to other notes, because we are all seeking the right balance of effort, intensity and recovery.
9. If you are struggling to recover from your sessions and feel like hell all the time, something is going wrong. Do what you can recover from. I get this ALL THE TIME. Stop honoring old workouts and the good 'ol days, and do what your body is capable of doing right now. Do not self-sabotage. If you're dreading your workouts, this is also a sign your training max is too high or your assistance is too demanding for where you are right now.
10. There is no "ONE WAY" to condition; every couple of years, a new study/fad comes out. First it was jogging, then H.I.I.T., then all Zone 1 and then it was all about Zone 2. All have been praised as the be-all-end-all. How about this - occasionally do all of these. You aren't going to die from AIDS because you did a long jog - and you aren't going to get out-of-shape because you did a 8 minute Prowler Death March. Unless you are training for something very specific, we all can afford to have a little fun here.
At the end of the day, and at the end of this article, you have to understand that this takes time, patience and consistently doing great things. If you've been out-of-shape for years, don't expect to be ready for selection in 3 weeks. Be honest with your readiness; it is often a harsh blow to the ego. But you will be surprised at how quickly you make progress when you have perspective and patience.