I always thought running was simple. Put one foot ahead of the other. Repeat, repeat, repeat...

But it's actually a lot trickier than that as I've learnt over the past few months. For one thing, if you've been sedentary like me for decades, there's a lot of work to be done to get prepped to do a race safely, even a fun run like the 5km which I am doing on Sunday at The Straits Times Run in the City.

Many people mistakenly believe that running is all about building one's stamina. And all they do for training is running and nothing else.

But running involves a lot more than that, and core fitness - to help your body maintain the correct posture while running - is something my personal trainer Mohamed Faizal has been keen for me to build up. He's been putting me through the paces at the True Fitness gym over the last few months.

Here are some of the moves I've been doing:

1. Crawl & Plank

I stand with my feet shoulder width apart. Then crawl into a plank. Then back up again. The challenge here is to keep my back straight.

2. Wall Roman twist.

Another exercise to build my core, and obliques.

I sit with my back against a wall. With a ball in hand, squeeze the core and obliques and twist so that the ball touches the wall on each side, near your hip. Shoulders should not leave the wall.

3. Wall squats

This drill to build up my quads is a real killer. It is A LOT harder than it looks.

Essentially, I stand against a wall and bend my knees till I am in a sitting position. Hold. For. As. Long. As. Possible.

For me that was about seven seconds when I first started. I can occasionally do 10-12sec now, but this is my least favourite exercise.

4. Bend over and reach

This is more of a strengthening exercise, to help me stop slouching and leaning forward. Maintaining my posture means I am more efficient during the run.

I stand slightly away from a wall. Feet hip-width apart. Keeping my back straight, I bring a ball down to touch the wall, then lift the ball above my head.

5. Bosu Tap and Touch

Looks easy but if done with enough reps, this leaves my glutes burning.

Essentially I lift one leg at a time and tap the top of the Bosu ball. Keep posture straight and don't sway. Repeat.

The drills are timeless and can be done regardless of what you're building up for.

The biggest benefit of having a personal trainer, like I'd mentioned previously, is that he keeps a close eye on my form. And makes sure I execute moves correctly and safely. Even when I am on the treadmill.

So Faizal has been correcting my posture - I tend to lean forward - by making me straighten up considerably over the last few months, which has lessened the stress on my lower back.

Killing the Funky Chicken

He's also corrected my arm movement when running. For some reason, my elbows tend to point outward slightly when I run, resulting in my arms being positioned like chicken wings.

In essence, I was doing the Funky Chicken Dance when running. It's not correct, and not cool. I was told to kill the "chicken".

I've mostly succeeded though it sometimes tends to rear its ugly head, especially when I am tired.

Hop Along Cassidy

Faizal also spotted another problem - my gait. See, instead of just putting one foot ahead of the other, my right leg tends to swing out ever so slightly. I've been doing a Hop Along Cassidy, which is why my right knee and hip have been acting up.

This, I must admit, is hard to fix. Especially since it is not particularly obvious to me (unlike the Funky Chicken).

But to the 4,000 runners who will join me for the 5km at the ST Run on Sunday, don't worry: Even if I do the Funky Chicken or the Hop Along Cassidy, I promise I won't elbow or trip you!

Keep a lookout for our race guide in tomorrow's paper.