There are two possible approaches to take when cycling ‘training’:
1) See it as a route towards pleasure: forget about ‘proper’ training, ignore planning schedules and interval training, and simply cycle often and regularly in order to gain overall fitness (and enjoy the countryside...)
2) Set specific targets for speed and distance and when these goals are to be achieved, and set-up a specific training schedule that will allow you to meet these goals
Of course, neither is the ‘right’ approach, it simply depends on your own cycling goals and what you hope to achieve, and also which kind of cycling brings you pleasure. It is very possible to be a good and competent cyclist without intensive training, and for many people this is all that we want from cycling, but equally there is great satisfaction in achieving personal goals.
To get significantly faster, or to compete in local races, you will need to follow the second approach - a more structured approac to cycling. But for many people the goals of cycling are more straightforward: to lose weight, to maintain and improve general fitness levels and - most important of all - just to have a good time.
We can do that without specific training, and this ‘casual training’ has other advantages. The cyclist is unlikely to suffer from over-training (common among those who follow a rigorous schedule of cycling training) or too much pressure to achieve ever better times, and will not have weeks of peak performance and weeks of under-performance.Simply by getting out cycling quite frequently you will make a lot of progress, even if you won’t win the local cycling championships.
Even if you are simply cycling for pleasure it is sometimes beneficial to have personal goals as a means of motivating yourself. First decide what distance and time you are aiming for, and then see how much you can do at the moment. Now simply increase your distance by a few kilometres each couple of weeks until you reach your goal! Broad guide: perhaps 40 - 50 miles in three hours might be a reasonable 'end' goal.
Remember, even if you are cycling completely for pleasure you will still need to make some effort if you are to improve! Not necessarily the arduous efforts of interval training, but you should push yourself to maintain yourself in a harder gear than usual when going up your favourite hill, or race as hard as you can between two telegraph poles etc. 'Casual training', we might call it, or 'informal effort'.
When you get home you want to feel as if you have had a good ride and your legs are a bit tired, but you don't need to be so exhausted that you can't walk for the rest of the day.
So don’t be concerned if you can’t be bothered with training schedules or rigid regular commitments. Just get on your bike and start cycling anyway! There are a very large number of cyclists who simply cycle for the sheer pleasure it brings, and there is nothing wrong at all in being one of them.