Playing golf: On the green putting and advice

💬 [やさしく] comes from [やさしい], but here it changes to the form used before verbs: [やさしく打つ] = hit gently. You can reuse that pattern with many [い]-adjectives, like [はやい] → [はやく] in [はやく歩く].

💬 [強さ] means the degree of strength or force, made from [強い] by changing it into a noun. You'll see the same pattern in words like [長い] → [長さ] for length.

💬 [いい] is the everyday word for "good," but its related forms often come from older [よい], like [よく] for "well." That is why Japanese says [ちょうどよく] for "just rightly / with just the right amount," not [ちょうどいく].

💬 [ちょうどいい] is a very common set phrase for "just right," whether you mean force, timing, size, or temperature. You can swap in lots of things before it, like [この速さはちょうどいい] for "this speed is just right."