You can walk or ski almost everywhere in nature. However, you must be careful not to disturb anyone or destroy anything.
People who live close to natural areas have the right to enjoy their homes undisturbed. This is why you must not to walk or ski across the grounds of a house.
"Grounds" in this context means the area immediately around a private dwelling. There are no rules stipulating a minimum distance – what matters is whether you cause a disturbance.
Cultivated ground mainly refers to gardens, plant nurseries, park plantations and similar vulnerable sensitive areas. You must never cross the grounds of a house or cultivated ground, regardless of whether or not there is a risk of damaging the ground or vegetation.
There may be other types of grounds that you are not permitted to cross if this could result in damage. A forest plantation of tender tree plants should probably be regarded as being off limits for the same reason.
Another common example are growing crops. During the time of year when crops are susceptible to damage, you must keep away from them. However, when the ground is frozen and covered in snow, it's fine to cross a crop field on foot or on skis.
The Right of Public Access is subject to another condition whereby you are not permitted to cause damage or any other form of nuisance. However, it would be hard to claim that this applies to a golf course – at any rate – not during play and not on the greens (the areas of finely cut grass around the holes).
These greens are particularly vulnerable so walking on them would probably be regarded as trespassing.
Greens can also be damaged during the winter months by skiing and hiking . So please respect any fences or barriers. However, as long as you stay off the greens and tees (the tees are the areas in which players make their first stroke), you are generally permitted on a golf course if play is not in progress.