Because I have personally trained systematically for 10 years, I consider this basic common sense, and many people may not know it.

The post below from KeKeLi has gone viral, so I’m sharing it here for everyone to see.
1) The basic principle of strength training/muscle building is "approach the current muscle limit—cause slight damage to the body—spontaneous repair—muscle growth—repeat."
It can be simply understood as pushing the muscles to the limit, and they will grow.
2) In this process, your body first consumes resources and then replenishes, ultimately resulting in growth.
So you need to be able to endure the depletion first, then recover.
3) The recovery here relies on eating and sleeping.
Sleep provides a baseline, eating adds volume.
Not eating will prevent growth, but not sleeping can be deadly.
4) All training, including strength training, high-intensity interval training (HIIT), moderate to high-intensity cardio (running, stair climbing, jumping), as long as it makes you "pant heavily," is training your heart.
5) The principle of training the heart is the same as training muscles (because essentially, your heart is also a big muscle)—make it tired—rest and recover—become stronger.
6) The benefits of a stronger heart are numerous, such as increased endurance, greater strength, more effective blood pumping, the ability to walk longer distances, and less fatigue.
7) Therefore, I highly recommend everyone incorporate muscle training (both external and cardiovascular) into daily routines—it's like buying a little gold every day, a good thing.
8) But! (Key point) If your heart, body, or muscles are already very tired recently, it means your body is out of resources! You can't afford to keep going!
Doing moderate to high-intensity workouts at this point is like borrowing high-interest loans!!!
It's not worth it!!!
9) If you're already sleep-deprived, the only and best exercise is no exercise at all.
Just sleep.
10) After ensuring basic sleep, for most ordinary people, doing "moderate to low-intensity exercise + avoiding prolonged sitting (important) + getting sunlight" is enough to maintain a healthy baseline.
11) "Avoiding prolonged sitting" is even more valuable than working out.
12) Moderate to low-intensity activities include: 30-minute walks, brisk walking, amateur-level badminton, walking the dog, chasing a hat blown away by the wind, riding shared bikes, playing with kids.
As long as it makes you feel "I moved" and causes slight sweating, it counts.
Flying a kite during this season is also very good.
13) "Avoiding prolonged sitting" is easy to do—stand while scrolling social media, or stand up when drinking water.
No need for strict timing; just set a rule for yourself to "stand and do something."
14) Standing for too long isn't good either.
Avoid extremes.
15) My minimum daily exercise requirement is: 50 movements before starting work each morning.
It can be using resistance bands for 50 reps, 50 jumping jacks, squats, chest-opening stretches, jogging in place for 1 minute, or wall push-ups.
Anything that slightly accelerates your heart rate works.
Additionally, I keep a 7kg kettlebell in the living room, and whenever I boil water or get up, I swing it 10–50 times.
It’s also effective for maintaining muscle.
16) Try to consciously incorporate "interval training" into your daily life.
For example, during walks, pick up the pace for a few steps;
while playing badminton, intentionally increase intensity for a while, then rest;
after a morning of work, do 20 squats at lunch;
while waiting for a burger, do 15 incline push-ups at the counter;
jump and touch a leaf on the roadside (yes, just like high school boys).
No need to find a special place or prepare equipment.
Just don’t let your heart stay calm all the time, but also avoid constant high-intensity "pumping."
Scatter these small bursts throughout the day to keep your heart lively.
17) I also personally schedule at least 1–2 sessions per week of heart-pumping exercise, like badminton, hill climbing, brisk walking, aerobics, etc.
Choose the intensity based on recent fatigue.
In any case, your heart needs a "nutritional boost" once a week to feel good.
18) I know some people prefer to go to places like "Super Monkey" after work for group classes, which are quite intense.
If you can’t keep up, just take it easy, pause, keep your heart rate stable—totally fine.
No need to feel embarrassed; more intense exercise isn’t necessarily better. Overexerting is not strength, it’s stupidity.