Academic coach Dennis Chu used to go outdoors four times a week to play basketball or run along the Ulu Pandan Park Connector.
However, since the coronavirus outbreak, he has stayed indoors as much as possible, doing push-ups and sit-ups in his room.
"In a public place, there is no one to screen people's temperatures. Wearing a mask is also impractical, so this means no outdoor exercise," says Mr Chu, 26.
Fitness instructors who spoke to The Sunday Times say holing up at home is not an excuse to lie on the sofa and snack all day.
Instead, people can create their own workout routines to stay active indoors.
Fitness trainer Cheryl Tay, 33, who teaches classes at fitness studio Grityard, says: "Being indoors limits the type of exercise activities you can do, but there are ways to work around it."
Running up and down the stairs is one good way to fit in a cardio workout.
Alternatively, try exercising with household objects such as water bottles as weights and a chair as a prop to do exercises like dips and step-ups, says Ms Tay.
To work out without equipment, consider body-weight exercises such as jump squats, push-ups and burpees, with planks for core work, says part-time fitness instructor and personal trainer Joween Lin.
Ms Lin, 27, who teaches classes at fitness and boxing studio boOm, says: "People can also do pilates and yoga, since there are a lot of online videos that are easy to follow."
If workouts are not one's cup of tea, maybe fitness-related games will help.
An example is Ring Fit Adventure, an action role-playing game on the Nintendo Switch console that requires users to jog on the spot, squat and do other exercises to complete various stages in the game.
Here are some workouts to try indoors.
For a quick workout
Do each exercise for 20 seconds, followed by 10 seconds of rest. Six exercises make up one round. Complete a total of three rounds, with one minute of rest in between rounds.
Front arm raises: Start with your arms by your sides, with a bottle in each hand. Keep both arms straight and raise them in front of you to shoulder height with the bottles parallel to the floor and palms facing downwards. Bring the arms back to your sides and repeat.
Mountain climbers: Get into a high-plank position with your shoulders directly above your wrists. While keeping your arms straight, pull your right knee towards your midsection. Do the same with the left knee.
Shoulder press: With a bottle in each hand, bend your elbows and raise your arms to shoulder height so the bottles are at your ears. Push the bottles up and directly over your head, then lower the bottles back to ear level.
Reverse lunges: Start with your feet together, then step back with the left leg. Lower your hips until your front thigh is parallel to the floor, with your right knee over your ankle. Your left knee is bent behind you and close to the floor, with your left heel off the floor. Repeat with the other leg.
Dips: Start by sitting on a chair with your palms facing down and fingers gripping the edge of the seat. Your feet should be flat on the floor at hip distance apart. Move your torso forward and lift your butt off and away from the seat. Lower your body towards the floor, without touching the floor, as you hinge at your elbows and bend them to a 90-degree angle. Push yourself back to the start position with your arms fully extended.
Burpees: Start in a standing position and get into a squat with your palms on the floor. Kick your feet back into a high-plank position then immediately jump forward and bring the feet back into the squat before standing up. You can add a push-up after you kick the feet back or a jump after you stand up.
Total time: 11 minutes
For a good sweat
FIND INSPIRATION IN FITNESS VLOGS
Besides the workouts recommended by Ms Tay, fitness enthusiasts can also watch fitness vlogs - or video blogs - on YouTube.
For example, they can go to youtube.com/user/blogilates/videos to check out American fitness star Cassey Ho's channel Blogilates, which has almost five million subscribers. One of the fitness pioneers on YouTube, Ms Ho conducts sessions of Pop Pilates, which is pilates choreographed to catchy pop music.
There are plenty of other fitness channels one can follow, such as England-born fitness trainer Rebecca Louise's channel, that has various home workout videos, or Canada-born Maddie Lymburner's channel MadFit, which has more than one million subscribers.
• Workouts on this page are recommended by Ms Cheryl Tay
Do each exercise for 30 seconds, followed by 15 seconds of rest. Six exercises make up one round. Complete four rounds of the exercises, with one minute of rest in between rounds.
Goblet squats: Place a duffel bag on your forearms and hug the bag with your back straight. Squat until your thighs are parallel to the floor before coming back up.
Push-ups: Start in a high-plank position. You can put your knees on the floor to make it easier. Lower your chest to the ground as you bend your elbows, then push yourself back up until your arms are straightened.
Crunches: Lie on your back and raise both feet off the floor. Place your hands behind your neck and lift your shoulders off the floor, while engaging your abdomen and raising your torso.
Lateral arm raises: Start with your arms by your sides, with a bottle in each hand. While keeping your arms straight, raise them to the side until they are parallel to the floor, with palms facing downwards. Bring your arms down to your sides and repeat.
Step-ups: Step onto a chair and stand tall with both legs before coming down. You can use the bottles to do bicep curls as you step up or hug a duffel bag.
Plank: Start in a high-plank position and then go down to your forearms and keep them at 90 degrees. Hold your body in that position while keeping your core engaged.
Total time: 20 minutes
Feel the burn
Do each exercise for 45 seconds, followed by 20 seconds of rest. Six exercises make up a round.
Complete a total of five rounds, with one minute of rest in between rounds.
Romanian deadlifts: Stand with your feet shoulder-width apart while gripping the sides of a duffel bag. With your knees straight, hinge at your hips and lower the bag while keeping your back straight. Lower the bag until you feel the stretch in your hamstrings and glutes before slowly straightening back up. Keep the bag as close to your shins as possible. The movement should be slow and controlled.
Roll-ups: Hold the ends of a towel in both hands and lie on your back. Extend your arms over your head and roll yourself into a sit-up.
Bulgarian split squats: Start with one foot on the chair behind you while standing tall, with most of your weight on your front leg. Lean forward slightly as you bring your hips down and back, until your back knee almost touches the floor. Push your front foot into the floor as you stand back up.
Pikes: Start in a high-plank position with both feet on a towel. Keeping both legs straight, bring them in as much as you can while keeping your back flat. This is best done on a slippery surface.
Overhead lunges: Hold a duffel bag or bottle above your head, before stepping back with one leg into a lunge. The front thigh should be parallel to the floor and the back knee is bent and as close to the floor as possible.
Russian twists: Sit on the floor and raise your legs with your knees bent. Lean back slightly so your torso and thighs form a V shape. While holding a bottle between both hands, keep your balance in this position and twist your torso side to side, without moving your legs.
Total time: 35 minutes