Hi, these expressions are commonly used.

You can easily find people using "It's just a matter of." It's just a matter of visiting the right places. :) Or, "It's just a matter of pushing the right buttons." Or, "It's just a matter of asking the right people." Or, "It's just a matter of getting some fresh air." Or, "It's just a matter of working out a lot." Not that uncommon, really.

- It's simply / just a matter of being or doing... 'Fame is often simply a matter of being in the right place at the right time.' - It's a matter + noun: 'It's a matter of personal choice.' - It’s just / only a matter of 'time (before … ) 'It's surely / only / just a matter of time before he is found, isn't it? - It's correct to say 'it's just a matter of somebody doing something' but it is not common.