A flat table is holding a huge wooden cube. An attempt to move the box is met with resistance, which Newton preferred to call inertia, inertia of rest to be particular. But in inanimate things like this wooden block it is just the mass that contribute to inertia. However the more you want to accelerate its movement the more force you need
Now look at another block, half as heavy but accelerating thrice as fast. You will need greater force to "STOP" this block than to "START" the first.
In human beings however, it is not just mass (of stagnation) but also the duration that contribute to inertia. Every passing second that we spend in this dearth of activity makes it harder to get out of it. The brighter side of this coin is it applies similarly to inertia of motion. The more (in amount and/or duration) we are involved in activity easier it is to maintain this state. If this analogy appear bogus (by idea or content) I would like to say it in an old and even more bogus cliche "old habits die hard", Human beings are like brindled horses who prefer to be in the rut as long as possible. For us I guess change is tougher call than achievement. Some of this plight can surely be attributed, and thankfully so, to the properties of matter. But the rest is of course an outcome of our choice. It is surely our call to chose which inertia we want to belong to, would it be the inertia of motion where stopping us is not easy or inertia of rest where possibility of moving forward is hopelessly remote.