The biggest obstacle here would be ourselves. 
Self doubt is a powerful detergent and often draws us away from pursuing change in habit and environment. 
To overcome this, the relationship towards doubt will need to shift slightly. 

When doubt creeps in, start to notice its texture and quality and through this noticing remember that it may not be entirely accurate.

Remember that beyond doubt there has often been different outcomes.
Doubt has been proved wrong and right…

Doubting forms a curtain like illusion which can hinder our story.

It may require us to reach beyond current positions and levels of personal engagement with whatever the doubt is currently covering. 

There are indeed times when doubt is useful and has served a genuine protective purpose. 
It helps us think more critically about certain hard decisions, slowing us down before we head down the various paths that appear before us. 

I doubt i still have my keys.. did i leave them in the train?
As you may feel, this can be a very useful type of doubt.  
But compare it to:  
We should really buy some land.. But where? Sweden? It may be too cold. Or Portugal, but wont we be too isolated? How do we get the money? Or where exactly should i find this land? 

As you can see it becomes a perpetual journey down the ladder rather then up. 

So its a balancing act, of differentiating between useful doubt and self sabotaging doubt. 

Another challenge to face is that doubt does not always approach us directly and will at times gradually seep in from the peripheral, like a bath tub filling up slowly, and before you know it you have moved away from the very thing you had set your self out to do, 

So what can we do? Perhaps whenever we feel a friction towards a decision, action, task or project, we can take extra care to observe whether this friction is a cause of useful doubt or a self protective doubt which we no longer wish to bow down towards.

--                Winston Reynolds