The TikTok "12-3-30 treadmill workout" has garnered more than 2 million likes and the hashtag "#12330" more than 81 million views since it appeared in 2019. And while all those aspiring fitness fans are probably not doing the routine regularly, it's important for anyone thinking about trying it to know the hazards — and the smart modifications that can make it healthier and more enjoyable.

The routine is walking on a treadmill at an incline of level 12 for 30 minutes, at the speed of 3 miles an hour. That's the equivalent of walking up a very steep hill. It elongates the upper back and muscles between your neck and shoulder while compressing your chest and pecs.

That’s a formula for feeling lousy during the workout and after. Being discouraged from day one can make it hard to keep your promise to yourself to get more physical activity.

On a treadmill, most physical medicine experts advocate that you start with a gentle incline — level 2 to 4 — and don't increase it until you're comfortable doing 10 minutes at a steady pace. Then they advocate increasing time spent and the incline slowly over a couple of months.

Ultimately, practice interval training by doing whatever is your tough level for a few minutes and then reducing the incline. Also, you don't have to do it daily. Combine it with other aerobic activities.

Remember that trendy routines on social media are just that — trendy. You and your healthcare professionals are more reliable "influencers" of what kind of exercise is best for you.