THE BROADBAND METHOD
There is no point learning this with concentration and will power, they are forms of focussing. Starting off with an appropriate use of the senses, is important, the ability to switch it on.
The ability to switch it on is the first vital step. And I believe that to get the "knack" to switch it on, it's no good trying.
Look at any pidgeon or blackbird while eating. This form of sensing is so vital for survival that they interrupt any delicious meal. Notice how quickly they change between their focussed mode of seeing and their broadband mode - and the second the head is up, they are able to instantly turn off any self centered behaviour and register if anything dangerous is moving.
So, at first, it's important to do this for only a half minute at a time or even a ten seconds. If you want to make it a priority, then do it whenever you think about it, several times a day.
There are lots of reasons for starting with these short periods. Partly because if doing this - even trying to do this - is enjoyable, then you will want to repeat it. Partly to create a feeling of urgency - it's got to be done now, and in a minutes time it'll be too late. And partly, to realise that you can turn it on, any time, without doing anything to prepare for it.
Your subconscious knows how it feels to use the senses like this. A minute a day which is interesting or enjoyable is the best way to give your subconscious the signal that it's time to remember.