These are my suggestions that one can keep fit without expensive membership, finding buddies or lots of time to do the contortion pose you see online.
1. EXIT
In the morning, when you go to work and when you return from lunch. That is 2x a day , 10 x a week and 40x a month.
Time : 5 minutes maximum
Process : step by step, normal climbing of stairs. No need to sprint up, take double or triple steps, nobody watching except you.
2. Blue
3. Stand up

4. Tummy Tuck In
Not what you are thinking! I am not referring to abdominoplasty or stuff like that. This is a great secret of mine, hehe.
Each morning when you walk to the bus stop, MRT or carpark, tuck in your stomach muscles and firm it for a good 5-10 seconds. You can count with your fingers or mentally in your head, it does not matter. Once you get the hang of this exercise, you can do it as often as you like whenever you are waiting for the meeting to start, the train to come, the lift to open, in the queue, etc.
Time : 5-10 seconds
5. IMAGINE
What's nice about it is this resource is available to all, regardless of race, age or gender.
Time : 1 minute
I hope you find this 5 easy tips useful and feel free to forward to your friends and loved ones.
Till my next post, to your health, cheers !