To get the ABSOLUTE BEST RESULTS, you have to be working towards 150 minutes of moderate intensity activity per week AND that has to happen EVERY WEEK. "Going hard" once in a while is only going to FRUSTRATE you because you'll feel like you're doing all this work and getting NOTHING out of it. DON'T DO THAT TO YOURSELF! Focus on building the habit first.
Build the HABIT of exercise by getting it in 10 minutes a day twice a week every week. Or 20 minutes a day 3 days a week. Or 30 minutes a day 4 days a week. I DON'T REALLY CARE HOW YOU DO IT, I just want you to be consistent.
Once exercise becomes a part of your ROUTINE then you can increase the time to maximize your results. As the old saying goes "Don't try to boil the ocean", FOCUS ON CONSISTENCY FIRST!